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Prof. Chiara Mingarelli, Department of Physics, University of Connecticut, "Probing supermassive black hole mergers with pulsar timing", Graduate Student Seminar12:15pm
4/24
Prof. Chiara Mingarelli, Department of Physics, University of Connecticut, "Probing supermassive black hole mergers with pulsar timing", Graduate Student Seminar
Friday, April 24th, 2020
12:15 PM - 01:15 PM
Storrs Campus video conferencing
Prof. Chiara Mingarelli, Department of Physics, University of Connecticut
Probing supermassive black hole mergers with pulsar timing
Galaxy mergers are a standard aspect of galaxy formation and evolution, and most (likely all) large galaxies contain supermassive black holes. As part of the merging process, the supermassive black holes should in-spiral together and eventually merge, generating a background of gravitational radiation in the nanohertz regime. An array of precisely timed pulsars spread across the sky can form a galactic-scale gravitational wave detector in this band. I describe the current efforts to develop and extend the pulsar timing array concept, together with recent limits which have emerged from international efforts to constrain astrophysical phenomena at the heart of supermassive black hole mergers. -
Graduate Student Lukasz Kuna, Department of Physics, University of Connecticut, "Mesoscale Studies of Nanostructured Multi-Functional Materials", PhD Dissertation Defense10:00am
4/16
Graduate Student Lukasz Kuna, Department of Physics, University of Connecticut, "Mesoscale Studies of Nanostructured Multi-Functional Materials", PhD Dissertation Defense
Thursday, April 16th, 2020
10:00 AM - 12:00 PM
Storrs Campus Video meeting
Graduate Student Lukasz Kuna,
Department of Physics,
University of Connecticut
Mesoscale Studies of Nanostructured Multi-Functional Materials
In this dissertation, multiple studies centered around functional properties of materials for applications in devices and novel technologies are carried out utilizing a mesoscale modeling approach. The studies involve simulating the properties of dielectric nano/microstructures with coupled polar and elastic degrees of freedom and developing a greater understanding of their dependence on the structure size, morphology and applied external conditions. Of particular focus in this work are optical properties of electroactive materials including zero- and one-dimensional structures such as nanoparticles and nanowires, as well as mesoscopic functional properties of larger structures such as polycrystalline ceramics (with submicron grain sizes) and ferroelectric mesa structures. The first two research topics are focused on the band gap properties of 1-D semiconductors and modeling of ferroelectric mesa structures, each study serving as an important tool in progressing the understanding of these materials for functional applications. The final topic, comprising the larger portion of the work, presents a novel approach for studying transmission in nanocrystalline ceramics based upon wave-train theory, that is then utilized to predict light transmission in polycrystalline ceramics. In particular, simulations examining the optical properties modulation under different applied mechanical and electrical boundary conditions predict large changes to transmission, including switching from full transparency to opacity in some instances. The results presented in this dissertation highlight an extraordinary promise of functional nano- and microceramics for a wide range of advanced engineering applications. -
Prof. L. Levitov, Department of Physics, MIT, "Long-Lived Excitations, Directional Memory and Hydrodynamic Transport in Two-Dimensional Electron Fluids", Condensed Matter Physics Seminar9:00am
4/10
Prof. L. Levitov, Department of Physics, MIT, "Long-Lived Excitations, Directional Memory and Hydrodynamic Transport in Two-Dimensional Electron Fluids", Condensed Matter Physics Seminar
Friday, April 10th, 2020
09:00 AM - 10:00 AM
Storrs Campus online
Prof. L. Levitov, Department of Physics, MIT
Long-Lived Excitations, Directional Memory and Hydrodynamic Transport in Two-Dimensional Electron Fluids
It was found recently that 2D electron fluids can support collective excitations that are not subject to Landau's \(T^2\) dissipation [1,2,3]. This surprising behavior originates from the head-on carrier collisions, a process that dominates angular relaxation at not-too-high temperatures \(T \ll T_F\) due to the joint effect of Pauli blocking and kinematic constraints. As a result, a large family of exceptionally long-lived excitations emerges, associated with the odd-parity harmonics of momentum distribution. This leads to "tomographic" dynamics: fast 1D spatial diffusion along the unchanging velocity direction accompanied by a slow angular dynamics that gradually randomizes velocity orientation. The abnormally slow angular relaxation originates from correlated angular dynamics involving "lock-step'' angular displacements along the Fermi surface occurring in collinear two-particle collisions. The slow loss of directional memory is described as non-Brownian angular random walk, "superdiffusion" on the Fermi surface. The collective behavior with directional memory dominates at moderately long times, pushing the onset of conventional hydrodynamics to abnormally large timescales. The tomographic regime features an unusual hierarchy of time and length scales, resulting in scale-dependent transport coefficients. The scale dependence manifests itself in fractional-power current flow profiles and unusual conductance scaling vs. temperature and sample size. This exotic behavior can be directly probed by transport measurement techniques, as well as by momentum-resolved tunneling measurements.
1. P J Ledwith, H Guo, L Levitov, The Hierarchy of Excitation Lifetimes in Two-Dimensional Fermi Gases,
Annals of Physics 411, 167913 (2019)
2. P J Ledwith, H Guo, A V Shytov, L Levitov,
Tomographic Dynamics and Scale-Dependent Viscosity in Two-Dimensional Electron Systems,
Phys Rev Lett 123, 116601 (2019)
3. P J Ledwith, H Guo, L Levitov, Angular Dynamics and Directional Memory in Two-Dimensional Electron Fluids,
2019
Zoom Meeting: https://kth-se.zoom.us/j/123036826 -
Prof. G. Fernando, Department of Physics, University of Connecticut, "Quasi-two-dimensional organics, Hubbard ladders, and dynamic stability", Graduate Student Seminar12:15pm
4/3
Prof. G. Fernando, Department of Physics, University of Connecticut, "Quasi-two-dimensional organics, Hubbard ladders, and dynamic stability", Graduate Student Seminar
Friday, April 3rd, 2020
12:15 PM - 01:15 PM
Storrs Campus video conferencing
Prof. G. Fernando, Department of Physics, University of Connecticut
Quasi-two-dimensional organics, Hubbard ladders, and dynamic stability
This presentation is a summary of several projects we have been working on during the past few years.
Our work covers electronic structure calculations of selected organic materials, searches for Dirac and Weyl materials as well as many-body physics of small clusters. In addition, recent developments in time crystal ideas are being examined at the many-body level. Our main interests are focused on several active areas in condensed matter physics such as topological materials, phase separation in small Hubbard clusters, unconventional superconductivity such as odd-frequency or photo-molecular high temperature superconductivity, frustrated magnetic systems such as quantum spin liquids and transport properties in two-dimensional systems. In addition, there is an ongoing effort on probing some fundamental aspects of quantum mechanics.
The link to the presentation:
https://physics.uconn.edu/wp-content/uploads/sites/2234/2020/04/phys_seminar_apr3_20.pptx -
Dr. Raffaella DeVita, INFN Genoa and Jefferson Lab, "Hadron spectroscopy in the light quark sector", Particle, Astrophysics, and Nuclear Physics Seminar2:00pm
3/30
Dr. Raffaella DeVita, INFN Genoa and Jefferson Lab, "Hadron spectroscopy in the light quark sector", Particle, Astrophysics, and Nuclear Physics Seminar
Monday, March 30th, 2020
02:00 PM - 03:00 PM
Storrs Campus GS-413E
Dr. Raffaella DeVita, INFN Genoa and Jefferson Lab
Hadron spectroscopy in the light quark sector -
Prof. Masafumi Fukuma, Kyoto University , "Title/abstract TBA", Particle, Astrophysics, and Nuclear Physics Seminar2:00pm
3/23
Prof. Masafumi Fukuma, Kyoto University , "Title/abstract TBA", Particle, Astrophysics, and Nuclear Physics Seminar
Monday, March 23rd, 2020
02:00 PM - 03:00 PM
Storrs Campus GS-413E
Prof. Masafumi Fukuma, Kyoto University
Title/abstract TBA -
CANCELLED:, Dr. J. Nathan Hohman, Institute of Materials Science and the Department of Chemistry, University of Connecticut, CANCELLED: Condensed Matter Physics Seminar2:00pm
3/17
CANCELLED:, Dr. J. Nathan Hohman, Institute of Materials Science and the Department of Chemistry, University of Connecticut, CANCELLED: Condensed Matter Physics Seminar
Tuesday, March 17th, 2020
02:00 PM - 03:00 PM
Storrs Campus GS 119
CANCELLED:
Dr. J. Nathan Hohman,
Institute of Materials Science and the Department of Chemistry, University of Connecticut
Self-Assembly of Low-Dimensional Nanomaterials in Crystalline Ensemble
When reduced in size to the nanoscale, materials express compelling new phenomena. For example, a single layer abstracted from graphite leads to fantastic new properties in graphene, or a nanocrystal of gold takes on new optical properties as a nanoparticle. Making materials very small or very thin has been an easy way to prepare exciting new materials--for example, the 2D transition metal dichalcogenides (TMDCs) have a long history of investigation prior to the recent interest in their monolayers for applications in photovoltaics, electrocatalysts, and spintronic materials. 2D phases have been uncovered for a number of elements and binary semiconductors, although many compounds do not share the same propensity to form 2D structures. Through the use of hybrid materials like hybrid perovskites and metal organic chalcogenide assemblies (MOCHAs), low-dimensional nanostructures can be prepared that are part of a crystalline ensemble, unlocking new portions of the period table to the exploration of low-dimensional phases. Importantly, hybrid materials combine organic components which enables structural and electronic direction at the molecular scale. Here, we consider the structure and organization of mithrene- silver benzeneselenolate- a self-assembling layered hybrid structure, and examine its optoelectronic properties in the context of a 2D-like material. Synthetic manipulation of dimensionality and topology is used to prepare a family of related crystalline polymer systems, and the role of intermolecular forces and molecular geometry on the inorganic phases are considered in the context of transitions between 1D, 2D, and 3D coordination polymer systems. -
Due to the current health situation and concerns surrounding the Corona virus, we are canceling the Katzenstein Lecture and Banquet scheduled for Friday, March 13, 2020., CANCELLED: 24th Annual Katzenstein Distinguished Lecture4:00pm
3/13
Due to the current health situation and concerns surrounding the Corona virus, we are canceling the Katzenstein Lecture and Banquet scheduled for Friday, March 13, 2020., CANCELLED: 24th Annual Katzenstein Distinguished Lecture
Friday, March 13th, 2020
04:00 PM - 05:00 PM
Storrs Campus Student Union Theater
Due to the current health situation and concerns surrounding the Corona virus, we are canceling the Katzenstein Lecture and Banquet scheduled for Friday, March 13, 2020.
Presented by the UConn Physics Department, the Katzenstein Distinguished Lecture series continues this spring. This year's program features Professor Donna Strickland of the University of Waterloo, 2018 Nobel Prize winner in Physics for co-inventing chirped pulse amplification, a technique for creating high-intensity ultrashort optical pulses. More information about Professor Strickland can be found at https://physics.uconn.edu/2020/03/04/professor-donna-strickland-katzenstein-distinguished-lecturer-march-13-2020/ -
Prof. A. Wuosmaa, Department of Physics, University of Connecticut, "Exotic Nuclei -- Modern Directions in Nuclear Physics", Graduate Student Seminar12:15pm
3/13
Prof. A. Wuosmaa, Department of Physics, University of Connecticut, "Exotic Nuclei -- Modern Directions in Nuclear Physics", Graduate Student Seminar
Friday, March 13th, 2020
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. A. Wuosmaa, Department of Physics, University of Connecticut
Exotic Nuclei -- Modern Directions in Nuclear Physics
The study of so-called "exotic nuclei" -- atomic nuclei with a large imbalance between the number of neutrons and protons -- is a major focus of nuclear-physics research today. Our understanding of the structure of nuclei far from stability is rather poor in comparison to what we know about stable nuclei, and that knowledge is important for understanding, for example, violent events in the cosmos responsible for the synthesis of the chemical elements. I will discuss some basics of nuclear structure, some examples where nuclear structure influences astrophysics, and how we can study the properties of exotic nuclei in the laboratory. Finally, I will describe a new accelerator facility that will be completed within the next two years which will enable a deeper understanding of the properties of exotic nuclei and will provide many new opportunities for research. -
Dr. Sumanta Bandyopadhyay, Nordita, "Superconductivity in a nonhermitian system and Berezinksii classification ", Condensed Matter Physics Seminar2:00pm
3/11
Dr. Sumanta Bandyopadhyay, Nordita, "Superconductivity in a nonhermitian system and Berezinksii classification ", Condensed Matter Physics Seminar
Wednesday, March 11th, 2020
02:00 PM - 03:00 PM
Storrs Campus GS 119
Dr. Sumanta Bandyopadhyay,
Nordita
Superconductivity in a nonhermitian system and Berezinksii classification
We have investigated the effects of nonhemriticty on superconducting states. Nonhermiticity enters our system due to electrons leaking out of/into (in case of pumping) the system. We have explicitly constructed several unconventional pairing amplitudes in nonhermitian systems in thep resence and absence of the particle-hole symmetry. We find nonhermitian dynamics induces odd frequency superconducting states, and we present the related experimental observables. We have further studied the robustness of the Berezinskii classification [1] of anomalous pairing amplitude in the presence of the nonhermiticity and shown that SP∗OT∗=−1 symmetry withstands nonhermiticity. -
CANCELLED:, Dr. A. B. Belonoshko, Department of Physics, Royal Institute of Technology, Sweden, CANCELLED: Condensed Matter Physics Seminar2:00pm
3/10
CANCELLED:, Dr. A. B. Belonoshko, Department of Physics, Royal Institute of Technology, Sweden, CANCELLED: Condensed Matter Physics Seminar
Tuesday, March 10th, 2020
02:00 PM - 03:00 PM
Storrs Campus GS 119
CANCELLED:
Dr. A. B. Belonoshko,
Department of Physics, Royal Institute of Technology, Sweden
Iron under extreme conditions
I will report the latest theoretical data on the iron phase diagram. A particular emphasis will be on the stabilization of the high-PT body-centered cubic (bcc) Fe under conditions of the Earth Inner Core [1] and how its stabilization interfere in the interpretation of iron melting curve and resolution of related enigmatic questions.
The mechanism of the high-PT bcc Fe phase stabilization is quite unique. The atoms in this structure move at times as in a liquid [2]. Therefore, the mean square displacement never saturates and the diffusion coefficient and the viscosity of the bcc Fe are similar to those in very viscous liquid [3].
Recently, our theoretical prediction of the stability of high-PT bcc Fe phase [1,4] was confirmed by diamond anvil cell experiments [5]. Interesting, that when a number of the experimental studies analyzed with the knowledge of the physics of the bcc Fe phase, those experiments confirm the stability of the new phase rather than contradict it.
I will show how the X-ray diffraction pattern of the bcc Fe looks like and discuss whether similar XRD patterns have already been observed in Fe high-PT melting experiments. I will demonstrate that the stabilization of the bcc phase was at times misinterpreted as melting.
The similarity of the bcc and liquid iron under extreme conditions of pressure and temperature revives the speculations on the existence of the critical solid-liquid point.
Acknowledgments: This work was supported by the Swedish Research Council.
[1] A. B. Belonoshko, T. Lukinov, J. Fu, J. Zhao, S. Davis, S. I. Simak Nature Geoscience 10, 312 (2017).
[2] https://www.youtube.com/watch?v=s5Rl7mtxiEY
[3] A. B. Belonoshko, J. Fu, T. Bryk, S. I. Simak, M. Mattesini, Nature Communications 10, 1-7 (2019).
[4] A. B. Belonoshko, R. Ahuja, B. Johansson, Nature 424, 1032 (2003).
[5] R. Hrubiak, Y. Meng, G. Shen, arXiv:1804.05109 Experimental evidence of a body centered cubic iron at the Earth's core conditions. -
Dr. Ali Kaya, Department of Physics, Harvard University, "Challenging the initial condition prescriptions in quantum cosmology", Physics Colloquium (Dr. Ali Kaya)3:30pm
3/6
Dr. Ali Kaya, Department of Physics, Harvard University, "Challenging the initial condition prescriptions in quantum cosmology", Physics Colloquium (Dr. Ali Kaya)
Friday, March 6th, 2020
03:30 PM - 04:30 PM
Storrs Campus BPB-131
Dr. Ali Kaya, Department of Physics, Harvard University
Challenging the initial condition prescriptions in quantum cosmology
Determining the initial state of the universe is a challenging problem in quantum cosmology and there are popular suggestions like the no boundary (Hawking & Hartle) and the tunneling (Vilenkin) prescriptions.
After briefly reviewing the problem, we argue that the quantum theory of gravity must resolve the big-bang singularity either by yielding a regular past eternal evolution or by a smooth finite beginning; in both cases the initial state can in principle be totally arbitrary that need not to be restricted by any ad-hoc principle. We illustrate this point in a minisuperspace toy model where there is a smooth beginning of the universe provided by the matter Hamiltonian degenerating to the zero operator. This simple model also illustrates how quantum gravity may resolve the big-bang singularity. -
Prof. A. Balatsky, Department of Physics, University of Connecticut and NORDITA, "Materials Informatics and Quantum Matter ", Graduate Student Seminar12:15pm
3/6
Prof. A. Balatsky, Department of Physics, University of Connecticut and NORDITA, "Materials Informatics and Quantum Matter ", Graduate Student Seminar
Friday, March 6th, 2020
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. A. Balatsky, Department of Physics, University of Connecticut and NORDITA
Materials Informatics and Quantum Matter
High-throughput calculations using first-principles methods in combination with approaches from data mining and machine learning fields have enabled a new stage in accelerated discovery of functional materials with special properties. I will present newly developed Organic Materials Database (OMDB, https://omdb.diracmaterials.org/) and discuss use of these methods. Our platform hosts thousands of electronic structures of synthesized organic materials [1] and is a useful tool in searching for novel materials. I will also discuss the implemented tools to predict and search magnetic structure factors and exchange coupling of organic materials in our database. Our work is a step towards a new way to search for novel functional materials characterized by a specific pattern in their electronic structure, for example, Dirac materials, topological insulators [2,3]. I will also present the ongoing work on the dynamics of quantum matter, where we predict transient collective instabilities in driven quantum systems [4].
[1] Stanislav S. Borysov http://et.al, (2017), PLoS ONE 12(2): http://e0171501.doi:10.137 https://doi.org/10.1371/journal.pone.0171501
[2] R. M. Geilhufe, S. S. Borysov, D. Kalpakchi, A.V. Balatsky, Physical Review Materials 2:2, (2018): 024802
[3] R. Matthias Geilhufe, Bart Olsthoorn, Alfredo D. Ferella, Timo Koski, Felix Kahlhoefer, Jan Conrad and Alexander V. Balatsky, Phys. Status Solidi RRL, 2018, 12, 1800293. S. Borysov et al, npj Computational Materials volume 4, Article number: 46 (2018)
[4] A Pertsova, AV Balatsky, Dynamically Induced Excitonic Instability in Pumped Dirac Materials, Annalen der Physik, 1900549 (2020) -
Prof. M. Gai, Department of Physics, University of Connecticut, "The Big Bang", Graduate Student Seminar12:15pm
2/28
Prof. M. Gai, Department of Physics, University of Connecticut, "The Big Bang", Graduate Student Seminar
Friday, February 28th, 2020
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. M. Gai, Department of Physics, University of Connecticut
The Big Bang
The Big Bang theory is one of the most fundamental theory of nature. In particular Big Bang Nucleosynthesis (BBN) is a parameter free theory, that gave one of the first and strongest evidence for the Big Bang theory. Current observation of primordial elements (that were produced during BBN), that are measured in some cases with an accuracy nearing 1%, are predicted at the same level of accuracy, with excellent agreement with observation. But one nagging problem remains: the production of 7Li in BBN is approximately a factor 3 and close to 5 sigma smaller than the prediction of BBN. This problem has been known over the last forty years as the "Primordial 7Li Problem".
We will review the Big Bang theory and BBN and describe an attempt to solve the lithium problem in the Master work of Emily Kading at UConn. We conclude that currently, there is still no standard solution to the lithium problem. -
Charles Reynolds Distinguished Lecture, Charles Reynolds Distinguished Lecture (Prof. Peter Abbamonte, U. of Illinois)3:30pm
2/21
Charles Reynolds Distinguished Lecture, Charles Reynolds Distinguished Lecture (Prof. Peter Abbamonte, U. of Illinois)
Friday, February 21st, 2020
03:30 PM - 04:30 PM
Storrs Campus BPB-131
Charles Reynolds Distinguished Lecture
"Bose Condensation of Excitons in a Transition Metal Dichalcogenide"
Professor Peter Abbamonte
University of Illinois
Urbana, IL
Bose condensation has shaped our understanding of macroscopic quantum phenomena, having been realized in superconductors, atomic gases, and liquid helium. Excitons are bosons that have been predicted to condense into either a superfluid or an insulating electronic crystal. But definitive evidence for a thermodynamically stable exciton condensate has never been achieved. In this talk I will describe our use of momentum-resolved electron energy-loss spectroscopy (M-EELS) to demonstrate the existence of an exciton condensate in the transition metal dichalcogenide semimetal, 1T‐TiSe2. This phase of matter was predicted in the 1960's and nicknamed "excitonium" by Halperin and Rice, but not realized for certain until now. I will discuss the experimental signature of exciton condensation, a plasmon that disperses to zero energy at the transition temperature, and latest results on its stability against carrier doping and hydrostatic pressure. -
Dr. Evan Philip, Department of Physics & Astronomy, Stony Brook University, "Chiral Photocurrents and Terahertz Emission in Dirac/Weyl Semimetals", Condensed Matter Physics Seminar2:00pm
2/19
Dr. Evan Philip, Department of Physics & Astronomy, Stony Brook University, "Chiral Photocurrents and Terahertz Emission in Dirac/Weyl Semimetals", Condensed Matter Physics Seminar
Wednesday, February 19th, 2020
02:00 PM - 03:00 PM
Storrs Campus GS 119
Dr. Evan Philip, Department of Physics & Astronomy, Stony Brook University
Chiral Photocurrents and Terahertz Emission in Dirac/Weyl Semimetals
I will start with an introduction to Dirac/Weyl semimetals and chiral anomaly. We will then look at a new mechanism for photocurrents in Dirac/Weyl semimetals that relies on the chiral anomaly. I will also discuss terahertz emission from the Weyl semimetal TaAs induced by a near-infrared laser, where Weyl fermions play a central role. We will conclude with remarks on some potential applications of these works. -
Dr. I. Zaliznyak, Brookhaven National Laboratory, "Entropic elasticity and negative thermal expansion in crystalline solids", Condensed Matter Physics Seminar2:00pm
2/18
Dr. I. Zaliznyak, Brookhaven National Laboratory, "Entropic elasticity and negative thermal expansion in crystalline solids", Condensed Matter Physics Seminar
Tuesday, February 18th, 2020
02:00 PM - 03:00 PM
Storrs Campus GS 119
Dr. I. Zaliznyak, Brookhaven National Laboratory
Entropic elasticity and negative thermal expansion in crystalline solids
While most solids expand when heated, some materials show the opposite behavior: negative thermal expansion (NTE). NTE is common in polymers and biomolecules, where it stems from the entropic elasticity of an ideal, freely-jointed chain. The origin of NTE in solids had been widely believed to be different, with phonon anharmonicity and specific lattice vibrations that preserve geometry of the coordination polyhedra -- rigid unit motions (RUMs) -- as leading contenders for explaining NTE. Our neutron scattering study of a simple cubic NTE material, ScF3, overturns this consensus [1]. We observe that the correlation in the positions of the neighboring fluorine atoms rapidly fades on warming, indicating an uncorrelated thermal motion, which is only constrained by the rigid Sc-F bonds. These experimental findings lead us to a quantitative, quasi-harmonic theory of NTE in terms of entropic elasticity of a Coulomb floppy network crystal, which is applicable to a broad range of open framework solids featuring floppy network architecture [2]. Our theory is in remarkable agreement with experimental results in ScF3, accurately describing NTE, phonon frequencies, entropic compressibility, and structural phase transition governed by entropic stabilization of criticality. We thus find that NTE in a family of insulating ceramics stems from the same simple and intuitive physics of entropic elasticity of an under-constrained floppy network that has long been appreciated in soft matter and polymer science, but broadly missed by the "hard" condensed matter community.
Our results reveal the formidable universality of the NTE phenomenon across soft and hard matter [1,2].
[1] D. Wendt, et al., Sci. Adv. 5: eaay2748. (2019).
[2] A. V. Tkachenko, I. A. Zaliznyak. arXiv:1908.11643 (2019). -
Dr. Andrey Sadofyev, Los Alamos National Laboratory, "Spin polarization of gauge bosons in rotating plasma", Particle, Astrophysics, and Nuclear Physics Seminar2:00pm
2/17
Dr. Andrey Sadofyev, Los Alamos National Laboratory, "Spin polarization of gauge bosons in rotating plasma", Particle, Astrophysics, and Nuclear Physics Seminar
Monday, February 17th, 2020
02:00 PM - 03:00 PM
Storrs Campus GS-413E
Dr. Andrey Sadofyev, Los Alamos National Laboratory
Spin polarization of gauge bosons in rotating plasma
I will show that the chiral vortical effect (CVE) known to take place for massless fermions in a rotating system can be, in fact, generalized to particles of arbitrary spin. These effects are particularly interesting since they describe the polarization of quarks, gluons, and photons in rotating QGP produced in heavy-ion collisions. For gauge bosons the local polarization current is not gauge invariant making it harder to use this object on practice. This issue can be resolved if one focuses on a class of gauge-invariant but non-canonical polarization currents of gauge bosons known as zilches. I will further show that CVE for gauge bosons has a counterpart in the general zilch current - zilch vortical effect (ZVE) and discuss how ZVE arises in a simple theoretical setup. -
Prof. G. Dunne, Department of Physics, University of Connecticut, "Scientific Communication: Preparing a Talk, a Proposal, or a Paper", Graduate Student Seminar12:15pm
2/14
Prof. G. Dunne, Department of Physics, University of Connecticut, "Scientific Communication: Preparing a Talk, a Proposal, or a Paper", Graduate Student Seminar
Friday, February 14th, 2020
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. G. Dunne, Department of Physics, University of Connecticut
Scientific Communication: Preparing a Talk, a Proposal, or a Paper
An important part of the work of a scientist is to communicate clearly the results of their work, in a way that can be understood by the appropriate audience: scientific, political or general. In this talk I discuss some tips for preparing a paper, a seminar or a proposal, and encourage you to think carefully about this aspect of your work. The good news is that with a little dedicated effort it is a sure way to stand out from the pack and have your work recognized. -
Prof. Lorenzo Sorbo, Department of Physics, University of Massachusetts Amherst, "Particle production during inflation: a case study", Particle, Astrophysics, and Nuclear Physics Seminar2:00pm
2/10
Prof. Lorenzo Sorbo, Department of Physics, University of Massachusetts Amherst, "Particle production during inflation: a case study", Particle, Astrophysics, and Nuclear Physics Seminar
Monday, February 10th, 2020
02:00 PM - 03:00 PM
Storrs Campus GS-413E
Prof. Lorenzo Sorbo, Department of Physics, University of Massachusetts Amherst
Particle production during inflation: a case study
In this talk I will quickly review primordial inflation. After arguing that axion-like inflatons are especially well motivated, I will discuss how a derivative coupling of a pseudoscalar inflaton to vector and to fermions fields can amplify significantly the mode functions of those degrees of freedom which, in their turn, can lead to a very rich phenomenology. -
Prof. Reynold E. Silber, Department of Geology and Geophysics, Yale University, "Transport properties of liquid transition metals at extreme conditions: a lesson from metallic glasses with the forbidden symmetry", Physics Colloquium (Prof. Reynold Silber)3:30pm
2/7
Prof. Reynold E. Silber, Department of Geology and Geophysics, Yale University, "Transport properties of liquid transition metals at extreme conditions: a lesson from metallic glasses with the forbidden symmetry", Physics Colloquium (Prof. Reynold Silber)
Friday, February 7th, 2020
03:30 PM - 04:30 PM
Storrs Campus BPB-131
Prof. Reynold E. Silber, Department of Geology and Geophysics, Yale University
Transport properties of liquid transition metals at extreme conditions: a lesson from metallic glasses with the forbidden symmetry
The Earth's core is a giant heat engine that supports the existence of life on our planet by providing heat to drive mantle convection, plate tectonics and volcanism. The convection of a liquid iron (Fe) alloy in the outer core generates the Earth's magnetic field. However, transport properties of liquid Fe-alloys (e.g., electrical, thermal and viscous transport properties) at extreme core conditions are some of the least constrained parameters. The high pressure experimental measurements of the transport properties are extremely challenging and a general theoretical understanding of the structures of liquid transition metals is still incomplete. Recent successful electrical resistivity measurements of liquid Fe, Ni and Fe-Si alloy at pressures up to 24 GPa show the invariant electrical resistivity along the melting boundaries. It was demonstrated that the Icosahedral Short Range Order (ISRO) structures in liquid transition metals and alloys strongly modulate transport properties at extreme conditions. Supporting evidence for the presence of the ISRO in the Earth's and other terrestrial outer cores comes from the recently discovered quasi-crystalline phases in natural metallic glasses with the forbidden symmetry, previously considered impossible to exist in nature. However, the existence of forbidden fivefold symmetry is not possible without super-cooling of metallic glass forming liquids that contain ISRO structures. Thus, metallic glasses represent one of the convergence points between planetary science and materials science. Here, I first discuss a new paradigm imposed by the ISRO structures on the transport properties of the outer cores of terrestrial planetary bodies. The discussion is then extended toward the important role ISROs play in formation of metallic glasses with exotic properties. Furthermore, I examine the potential application of high pressures toward manufacturing of metallic glasses with customizable concentration of structures with ISRO or any other forbidden symmetry. Considering the important role of metallic glasses in the high tech industry, this research has significant cross-disciplinary implications. -
Prof. I. Sochnikov, Department of Physics, University of Connecticut, "Quantum sensing and imaging of materials", Graduate Student Seminar12:15pm
1/31
Prof. I. Sochnikov, Department of Physics, University of Connecticut, "Quantum sensing and imaging of materials", Graduate Student Seminar
Friday, January 31st, 2020
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. I. Sochnikov, Department of Physics, University of Connecticut
Quantum sensing and imaging of materials
I will describe our recent discoveries of fascinating emergent phenomena in several quantum materials, including high temperature and low temperature superconductors. I will provide details of our state-of-the-art experimental systems with a focus on quantum sensing and mesoscopic imaging.
Additionally, I will present my view of what a successful doctorate in experimental physics includes, as well as, what you might expect from our Ph.D. program and how to be successful in it. -
Prof. Dale Kocevski, Colby College, "Connecting Black Hole Growth and Galaxy Evolution Across Cosmic Time", Physics Colloquium (Prof. Dale Kocevski)3:30pm
1/24
Prof. Dale Kocevski, Colby College, "Connecting Black Hole Growth and Galaxy Evolution Across Cosmic Time", Physics Colloquium (Prof. Dale Kocevski)
Friday, January 24th, 2020
03:30 PM - 04:30 PM
Storrs Campus BPB 131
Prof. Dale Kocevski, Colby College
Connecting Black Hole Growth and Galaxy Evolution Across Cosmic Time
Supermassive black holes, and the active galactic nuclei (AGN) that they power, are thought to play an integral role in the evolution of galaxies by acting to regulate, and eventually suppress, the star formation activity of their host galaxies. I will discuss recent efforts to test this proposed connection by studying the demographics of galaxies experiencing active black hole growth. In particular, I will highlight results obtained using infrared imaging from the Hubble Space Telescope, which has allowed us to study galaxies back when the Universe was a quarter of its current age. It is during this era of cosmic history that black hole growth and star formation activity in the Universe are at their peak. I will discuss what Hubble has revealed about the mechanisms that fuel AGN activity at this epoch and the connection between black hole growth and the emergence of the first generation of passive galaxies in the Universe. I will also discuss future work planned with Hubble's successor, the James Webb Space Telescope, which will soon allow us to view the first galaxies and black holes to form after the Big Bang.
Cookies will be served prior to the talk, at 3:00 p.m. outside BPB-131 -
Prof. R. Jones, Department of Physics, University of Connecticut, "Resolving a Mystery in QCD with High Energy Photons", Graduate Student Seminar12:15pm
1/24
Prof. R. Jones, Department of Physics, University of Connecticut, "Resolving a Mystery in QCD with High Energy Photons", Graduate Student Seminar
Friday, January 24th, 2020
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. R. Jones, Department of Physics, University of Connecticut
Resolving a Mystery in QCD with High Energy Photons
Almost immediately after QCD was recognized as the correct theory of the strong force, it was realized that in addition to the stable nuclear particles (known hadrons) that had already been seen, other entire families of unstable nuclear particles should also exist, which decay into the known hadrons. These new particles, collectively known as "exotic hadrons", include glueballs, hybrids, tetraquarks, and pentaquarks. Experimental searches for exotics for the past 40 years have mostly turned up empty, until recently. I will describe recent results from the LHC that give convincing evidence of tetraquarks, and a new experiment recently begun at Jefferson Lab to search for hybrids. -
Dr. Matt Orr, California Institute of Technology, "Spatially Resolved Star Formation in Cosmological Zoom-in Simulations: Understanding the Role of Feedback in Scaling Relations", Astronomy Seminar2:00pm
1/22
Dr. Matt Orr, California Institute of Technology, "Spatially Resolved Star Formation in Cosmological Zoom-in Simulations: Understanding the Role of Feedback in Scaling Relations", Astronomy Seminar
Wednesday, January 22nd, 2020
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. Matt Orr, California Institute of Technology
Spatially Resolved Star Formation in Cosmological Zoom-in Simulations: Understanding the Role of Feedback in Scaling Relations
Cosmological simulations have evolved over the past two decades to match ever more restrictive constraints on galaxy formation and evolution. For much of this time, simulations struggled to match global properties of observed galaxies: stellar mass--halo mass relations, integrated star formation rates--gas masses (integrated Kennicutt-Schmidt), etc. However, the latest generation of zoom-in simulations is just now able to spatially resolve many of these galaxy scaling relations. In my talk, I will discuss several aspects of spatially resolved galaxy scaling relations in the FIRE (Feedback In Realistic Environments) suite of cosmological zoom-in simulations, among them: Kennicutt-Schmidt, star formation rate profiles, and line of sight gas velocity dispersions correlating with star formation rates. These projects all relating back to the idea that stellar feedback has a central role to play in the emergence of many of these galaxy scaling relations. I will explore how modern cosmological simulations like FIRE, and associated analytic models, are moving closer to observations, both in their results and their ability to model observables directly. -
Dr. Kiryl Pakrouski, Department of Physics, Princeton University, "Automatic design of Hamiltonians", Condensed Matter Physics Seminar2:00pm
1/10
Dr. Kiryl Pakrouski, Department of Physics, Princeton University, "Automatic design of Hamiltonians", Condensed Matter Physics Seminar
Friday, January 10th, 2020
02:00 PM - 03:00 PM
Storrs Campus GS 119
Dr. Kiryl Pakrouski, Department of Physics, Princeton University
Automatic design of Hamiltonians
We formulate an optimization problem of finding optimal Hamiltonians by analogy to the variational principle. Given a variational ansatz for a Hamiltonian we construct a loss function as a weighted sum of relevant Hamiltonian properties specifying thereby the search query. Using fractional quantum Hall effect as a test system we illustrate how the framework can be used to determine a generating Hamiltonian of a finite-size model wavefunction (Moore-Read Pfaffian and Read-Rezayi states) or to find optimal parameters for an experiment. We also discuss how the search for approximate generating Hamiltonians may be used to find simpler and more realistic models implementing the given exotic phase of matter by experimentally accessible interaction terms. -
Dr. GiBaik Sim, Department of Physics, Korea Advanced Institute of Science and Technology, "Interacting spin-3/2 and spin-1 Fermions : Topological superconductivity", Condensed Matter Physics Seminar2:00pm
1/7
Dr. GiBaik Sim, Department of Physics, Korea Advanced Institute of Science and Technology, "Interacting spin-3/2 and spin-1 Fermions : Topological superconductivity", Condensed Matter Physics Seminar
Tuesday, January 7th, 2020
02:00 PM - 03:00 PM
Storrs Campus GS 119
Dr. GiBaik Sim, Department of Physics, Korea Advanced Institute of Science and Technology
Interacting spin-3/2 and spin-1 Fermions : Topological superconductivity
In this talk, I will first discuss generic realization of topological superconductivity in three-dimensional quadratic band touching system. [1]
Based on the interacting Luttinger model, I exhibit that the absence of particle-hole symmetry leads the system to favor the special spin-quintet
superconductors with secondary spin-singlet pairing ; (i) uniaxial nematic phase with secondary spin-singlet pairing \( \left(S_{3z^2-r^2}+s\right)\), (ii) timereversal breaking phase with secondary spin-singlet pairing \( \left( S_{3z^2 -r^2} + S_{xy}+iS_{x^2-y^2} + s \right) \). \( \left(S_{3z^2-r^2}+s\right)\) phase possesses topologically non-trivial nodal rings and drumhead-like surface states. \( \left( S_{3z^2 -r^2} + S_{xy}+iS_{x^2-y^2} + s \right) \) phase contains topologically protected Bogoliubov Fermi pockets and corresponding zero-energy arc states. I will also argue
possible applications of this theory to YPtBi.
As a next step, I will introduce the spin-triplet superconductivity in the
newly discovered form of the topological semimetal, where spin-1 electrons
form triple-band crossings. [2] The peculiar property of spin-1 Fermions is that Fermi statistics rules out on-site spin-singlet pairing. Adopting the Landau theory of spin-triplet pairings, I exhibit that the system stabilizes two
distinct phases ; (i) time-reversal symmetric \(S_z\) phase, (ii) time-reversal breaking \(S_{x}+iS_{y}\) phase. Remarkably, both of these phases have gapless Bogoliubov quasiparticles and furthermore possess topological invariants for each nodal ring or Bogoliubov Fermi surface.
[1] G. Sim, A. Mishra, M. J. Park, Y. B. Kim, G. Y. Cho, and S. Lee, Physical Review B 100, 064509 (2019).
[2] G. Sim, M. J. Park, and S. Lee, arXiv:1909.04015 (2019). -
Dr. Julia Wildeboer, Max Planck Institute for the Physics of complex systems, "Tales from the Quantum Spin Liquid Crypt", Condensed Matter Physics Seminar4:00pm
12/12
Dr. Julia Wildeboer, Max Planck Institute for the Physics of complex systems, "Tales from the Quantum Spin Liquid Crypt", Condensed Matter Physics Seminar
Thursday, December 12th, 2019
04:00 PM - 05:00 PM
Storrs Campus GS-117
Dr. Julia Wildeboer, Max Planck Institute for the Physics of complex systems
Tales from the Quantum Spin Liquid Crypt
Two-dimensional frustrated quantum antiferromagnets can harbor a phase of matter called a quantum spin liquid .This state exhibits no conventional symmetry but emergent, topological order. Remarkably, the spin liquid state has fascinating features such as gapped fractionalized quasiparticle excitations with exotic quantum statistics making it a highly sought after state in the (topological) quantum computation community.
In this talk, I will review properties of a spin liquid state and discuss the concept of quantum entanglement which is an important diagnostic tool when it comes to uncovering the nature of a spin liquid state. I will introduce a family of fractional quantum Hall (FQH) lattice states. Using the Moore-Read lattice state as an example, I will demonstrate how ''FQH physics in lattice systems'' can advance the field by discussing the issue of inserting quasiholes and quasielectrons into the FQH lattice state, the insertion of the latter being impossible in continuum FQH states because of a singularity problem. -
Prof. A. Polkovnikov, Department of Physics, Boston University, "Periodically driven quantum systems", Condensed Matter Physics Seminar2:00pm
12/12
Prof. A. Polkovnikov, Department of Physics, Boston University, "Periodically driven quantum systems", Condensed Matter Physics Seminar
Thursday, December 12th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-117
Prof. A. Polkovnikov,
Department of Physics,
Boston University
Periodically driven quantum systems
In this talk I will give an overview of periodically driven (Floquet) quantum systems. In particular, after giving a general introduction I will discuss basic ideas of Floquet engineering, relation between the high frequency expansion and the Schrieffer-Wolff transformation, general questions of adiabaticity in such systems, heating and the ways to suppress it. -
Graduate Student Cheng Tu, Department of Physics, University of Connecticut, "Study HVP and HLbL contribution to the muon g - 2 using Lattice QCD ", PhD Dissertation Defense3:00pm
12/10
Graduate Student Cheng Tu, Department of Physics, University of Connecticut, "Study HVP and HLbL contribution to the muon g - 2 using Lattice QCD ", PhD Dissertation Defense
Tuesday, December 10th, 2019
03:00 PM - 05:00 PM
Storrs Campus GS-117
Graduate Student Cheng Tu,
Department of Physics,
University of Connecticut
Study HVP and HLbL contribution to the muon g - 2 using Lattice QCD
The hadronic vacuum polarization (HVP) contribution and long-distance hadronic light-by-light (HLbL) scattering contribution to the muon anomalous magnetic moment are evaluated by using lattice QCD. The HVP calculations are performed with 2 + 1 + 1 flavors of HISQ fermions at the physical pion mass from three ensembles, generated by the MILC collaboration. In the long-distance part of the HLbL contribution, we replace the QCD, four-current connected Green's function from previous HLbL study with the product of two independent πγγ amplitudes, which are joined by an analytic, position space pion propagator. The calculations are performed with near physical pion mass on four different lattice ensembles, which are generated by RBC/UKQCD Collaboration. -
Dr. Adrian Gozar, Applied Physics Department, Yale University , "Optical nano-imaging of novel quantum materials and hetero-structures.", Condensed Matter Physics Seminar2:00pm
12/10
Dr. Adrian Gozar, Applied Physics Department, Yale University , "Optical nano-imaging of novel quantum materials and hetero-structures.", Condensed Matter Physics Seminar
Tuesday, December 10th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS 117
Dr. Adrian Gozar, Applied Physics Department, Yale University
Optical nano-imaging of novel quantum materials and hetero-structures.
'Quantum materials' are platforms for observation of quantum effects at macroscopic scales. Their properties can be often combined in layered structures and are strongly sensitive to external stimuli, suggesting a plausible path towards a new generation of devices with 'on-demand' functionalities. We focus on expanding the material phase-space of these materials and also on finding new ways to probe their surface and interface properties. An example of novel graphitic structures produced in our lab is borophene, a 2D boron allotrope with potential technological uses in flexible electronics and as a precursor to metallic nanotubes. I will discuss synthesis and characterization of large area, up to 100 μm2 in size, single-crystals of borophene on copper surfaces and also ideas for device integration. Scanning near-field optical microscopy (SNOM) is able to probe electronic properties of surface or subsurface crystalline layers despite the presence of underlying metallic substrates. I will illustrate how the lateral and depth resolution are key advantages of SNOM as a non-invasive optical method for device characterization. I will also emphasize the power of this technique for obtaining fundamental information about electron dynamics in hetero-structures. An example is the generation and coupling to novel excitations such as surface Josephson plasma modes in an ultra-thin superconducting film. These results highlight SNOM as a non-invasive tool which is particularly useful for studying interface electron dynamics, imaging states with broken symmetry in correlated systems and topological materials as well as for probing structure, dielectric properties and emergent conduction channels in nano-structures and biological samples. -
Cancelled!, Prof. I. Sochnikov, Department of Physics, University of Connecticut, Cancelled: Graduate Student Seminar12:15pm
12/6
Cancelled!, Prof. I. Sochnikov, Department of Physics, University of Connecticut, Cancelled: Graduate Student Seminar
Friday, December 6th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Cancelled!
Prof. I. Sochnikov, Department of Physics, University of Connecticut
Quantum sensing and imaging of materials
I will describe our recent discoveries of fascinating emergent phenomena in several quantum materials, including high temperature and low temperature superconductors. I will provide details of our state-of-the-art experimental systems with a focus on quantum sensing and mesoscopic imaging.
Additionally, I will present my view of what a successful doctorate in experimental physics includes, as well as, what you might expect from our Ph.D. program and how to be successful in it. -
Graduate Student Razib Obaid, Department of Physics, University of Connecticut, "Single and multi-photon induced ionization in atoms and molecules", PhD Dissertation Defense10:00am
12/5
Graduate Student Razib Obaid, Department of Physics, University of Connecticut, "Single and multi-photon induced ionization in atoms and molecules", PhD Dissertation Defense
Thursday, December 5th, 2019
10:00 AM - 12:00 PM
Storrs Campus GS-117
Graduate Student Razib Obaid,
Department of Physics,
University of Connecticut
Single and multi-photon induced ionization in atoms and molecules
The response of atomic and molecular species to photoionization is being studied for decades now. These atoms and molecules respond characteristically upon absorption of photons. The interesting question is: how is the energy deposited into the atoms and molecules by absorption of photons ultimately dissipated? The advent and development of X-ray synchrotrons, free-electron lasers and the strong field optical lasers keep ushering new dimensions into this question in terms of the ability of following rapid sequence of events, and, otherwise, identifying hidden relaxation mechanisms.
Through the means of resonant excitation of valence and inner shell electrons of simple atom, such as neon, and cluster-like complex molecular system such as fullerene and endohedral fullerene, we investigated their relaxation mechanisms by absorption of single and multiple photons. At excitation above their characteristic resonances, we observed hitherto unknown time delayed relaxation mechanisms in the structural change of fullerene, interatomic Coulombic decay and incomplete charge transfer processes in endohedral fullerene, and two photon absorption in neon through observation of fluorescence. Furthermore, we also investigated the fragmentation and hydrogen migration dynamics in hydrocarbons to explore the energy dissipation question for biologically relevant systems. The work is worthwhile in that it contributes to the understanding of the ultrafast intrinsic dynamics of various processes and systems relevant to physics, chemistry, and biology. -
Dr. Fatma Aslam, University of Connecticut & Jefferson Lab, "Singularities in twist-3 distributions and QCD vacuum", Particle, Astrophysics, and Nuclear Physics Seminar3:00pm
12/4
Dr. Fatma Aslam, University of Connecticut & Jefferson Lab, "Singularities in twist-3 distributions and QCD vacuum", Particle, Astrophysics, and Nuclear Physics Seminar
Wednesday, December 4th, 2019
03:00 PM - 04:00 PM
Storrs Campus GS-117
Dr. Fatma Aslam, University of Connecticut & Jefferson Lab
Singularities in twist-3 distributions and QCD vacuum
Twist-3 Generalized Parton Distributions may provide an alternative source of information on quark orbital angular momentum. Additionally, twist-3 GPDs embody information on the spatial distribution of quark-gluon correlations. Spectator models are used to study general features that appear in twist-3 GPDs. We find in 1 loop calculations/spectator models that twist-3 generalized parton distributions exhibit discontinuities. In the forward limit these singular contributions grow into delta function contributions. These terms are essential for certain sum rules for twist 3 PDFs and neglecting these terms leads to an apparent violation of these sum rules. We identify these delta function terms with momentum components in the nucleon state that do not scale as the nucleon is boosted to infinite momentum. -
Dr. Brian Svoboda,National Radio Astronomy Observatory, "The earliest phases of high-mass star formation in the Milky Way", Astronomy Seminar2:00pm
12/4
Dr. Brian Svoboda,National Radio Astronomy Observatory, "The earliest phases of high-mass star formation in the Milky Way", Astronomy Seminar
Wednesday, December 4th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. Brian Svoboda,National Radio Astronomy Observatory
The earliest phases of high-mass star formation in the Milky Way
High-mass stars are key to regulating the interstellar medium, star formation activity, and overall evolution of galaxies, but their formation remains an open problem in astrophysics. In order to understand the physical conditions during the earliest phases of high-mass star formation, I will present observational studies we have carried out on dense molecular clouds that show no signatures of star formation activity. We identify several thousand dense, starless clump
candidates (SCCs) from the 1.1 mm Bolocam Galactic Plane Survey and systematically analyze their physical properties. We further investigate the 12 most high-mass SCCs within 5 kpc using the Atacama Large Millimeter/submillimeter Array (ALMA) to study their sub-structure at high spatial resolution. We find previously undetected low-luminosity protostars in 11 out of 12 SCCs, fragmentation equal to the thermal Jeans length of the clump, and no starless cores exceeding 30 solar masses. While uncertainties remain concerning the star formation efficiency in this sample, these observational facts are consistent with models where high-mass stars form from initially low- to intermediate-mass protostars that accrete most of their mass from the surrounding clump. I will also present on-going research studying gas inflow signatures with GBT/Argus and ALMA, and the dense core mass function with the JVLA. -
Dr. Fazel Tafti, Boston College, "Design Principles for the Kitaev Magnets with Emergent Majorana Fermions ", Condensed Matter Physics Seminar2:00pm
12/4
Dr. Fazel Tafti, Boston College, "Design Principles for the Kitaev Magnets with Emergent Majorana Fermions ", Condensed Matter Physics Seminar
Wednesday, December 4th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-117
Dr. Fazel Tafti, Boston College
Design Principles for the Kitaev Magnets with Emergent Majorana Fermions
Our progress toward the age of quantum computing requires a new class of materials with long-range spin entanglement and fractionalized excitations known as Majorana fermions. These elusive particles are theoretically predicted to exist in a spin liquid ground state inside a frustrated magnet. Candidate materials for magnetic frustration and the spin liquid state must have strong interactions but lack any magnetic ordering. Instead of an ordered ground state, these materials produce a quantum entangled ground state with coherent spin fluctuations. In this talk, I will explain how such ground states are constructed in magnetic materials by introducing valence bond solids and resonating valence bonds. I will focus on a special class of materials with honeycomb structure and strong magnetic frustration due to bond dependent ferromagnetic interactions. Such materials are described by a Kitaev Hamiltonian that consists of bond dependent anisotropic exchange interactions. I will explain why the current candidate materials have failed to satisfy the predictions of the theory, and provide a potential solution to improve such materials and achieve a true spin liquid ground state. -
Prof. Jie Wu, Westlake University, China, "Electronic nematicity in unconventional superconductors", Condensed Matter Physics Seminar2:00pm
11/26
Prof. Jie Wu, Westlake University, China, "Electronic nematicity in unconventional superconductors", Condensed Matter Physics Seminar
Tuesday, November 26th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS 119
Prof. Jie Wu, Westlake University, China
Electronic nematicity in unconventional superconductors
The mechanism of high temperature superconductivity is a long-standing mystery in condensed matter physics. Despite of the intensive efforts devoted to this topic since its discovery in 1987, the nature of the superconducting state and the normal state remains ambiguous. Starting from an unexpected observation that the voltage transverse to the current direction is not zero in high temperature superconductors (HTS), I will present our investigations for the underlying mechanism, which at the end leads to the picture of the spontaneous breaking of the rotational symmetry in the normal state of HTS. Such a peculiar state is named as the electronic nematic state, implying its origin is the electron-electron correlation and, more importantly, the motion of electrons is anisotropic in the Cu-O plane. This challenges the basics of the Fermi liquid theory that the electrons' motion is isotropic as the word "liquid" implies. By studying how the nematicity evolves with the temperature and the chemical doping, our experiments reach the conclusion that the high temperature superconductivity in fact emerges out of the electronic nematic state. Other unconventional superconductors, such as ruthenate and Fe-based superconductors, show very similar behavior, indicating the electronic nematicity may be deeply correlated with unconventional superconductivity.
I will also briefly discuss our findings of the dependence of the superconducting temperature on the superfluid density, the abnormal independence of the interface superconductivity on the chemical doping, and the charge cluster glass state in the vicinity of the superconductor-insulator transition. All these findings constitute a vague but coherent picture of HTS.
References:
1. J. Wu, A. T. Bollinger, X. He and I. Božović, "Spontaneous breaking of rotational symmetry in copper oxide superconductors", Nature 547, 432-435 (2017).
2. I. Božović, X. He, J. Wu and A. T. Bollinger, "Dependence of the critical temperature in overdoped copper oxides on superfluid density", Nature 536, 309-311 (2016).
3. J. Wu, A. T. Bollinger, J. Sun and I. Božović, "Hall effect in quantum critical charge cluster glass", Proc. Natl. Acad. Sci. USA 113, 4284-4289 (2016).
4. J. Wu, O. Pelleg, G. Logvenov, A. T. Bollinger, J. Sun, G. S. Boebinger, M. Vanević, Z. R adović and I. Božović, "Anomalous independence of interface superconductivity from carrier density", Nature Materials 12, 877-881 (2013). -
Dr. N. Wink, University of Heidelberg, "The gluon spectral function and its applications", Particle, Astrophysics, and Nuclear Physics Seminar2:00pm
11/25
Dr. N. Wink, University of Heidelberg, "The gluon spectral function and its applications", Particle, Astrophysics, and Nuclear Physics Seminar
Monday, November 25th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-413E
Dr. N. Wink, University of Heidelberg
The gluon spectral function and its applications
Despite their fundamental importance, reliable access to time-like correlation functions in QCD remains an unsolved problem. One way of accessing spectral functions in a theory is via numerical reconstruction based on data acquired in Euclidean space-time. After
general considerations concerning the analytic structure of correlation
functions it is shown how this information can be used to improve on existing spectral reconstruction techniques. The novel method is applied
to the gluon in Landau gauge and the result is used to access bulk and shear viscosity. -
Prof. Andrea Cavalleri Max Planck Institute for the Structure and Dynamics of Matter, Hamburg , "Controlling Quantum Materials with Light", Physics Colloquium (Prof. Andrea Cavalleri)3:30pm
11/22
Prof. Andrea Cavalleri Max Planck Institute for the Structure and Dynamics of Matter, Hamburg , "Controlling Quantum Materials with Light", Physics Colloquium (Prof. Andrea Cavalleri)
Friday, November 22nd, 2019
03:30 PM - 04:30 PM
Storrs Campus BPB 131
Prof. Andrea Cavalleri
Max Planck Institute for the Structure and Dynamics of Matter, Hamburg
Controlling Quantum Materials with Light
I will discuss how coherent electromagnetic radiation at infrared and TeraHertz frequencies can be used to drive collective excitations in solids nonlinearly. The driven cooperative response can yield new types functional control. I will for example discuss experiments in which phonons are manipulated, amplified and used to drive electronic coherences in solids. I will also discuss the physics of superconducting plasmons in layered superconductors and how these reveal new nonlinear THz phenomena. -
Prof. C. Roychoudhuri, Department of Physics, University of Connecticut, "Complex interaction processes we need to visualize that successfully fill up the quantum cup of a detector", Graduate Student Seminar12:15pm
11/22
Prof. C. Roychoudhuri, Department of Physics, University of Connecticut, "Complex interaction processes we need to visualize that successfully fill up the quantum cup of a detector", Graduate Student Seminar
Friday, November 22nd, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. C. Roychoudhuri, Department of Physics, University of Connecticut
Complex interaction processes we need to visualize that successfully fill up the quantum cup of a detector
Sensors are measuring tools. In any measurement, we have at least two different
kinds of interactants. We never know all there are to know about any one of these
interactants and the interaction processes that are mostly invisible. Yet, our
engineering innovation driven evolution is persisting for over five million years. It
is then important to articulate explicitly our Interaction Process Mapping Thinking
(IPM-T) that we keep applying in the real world without formally recognizing it. We
present how the systematic application of IPM-T removes century old wave-particle
duality by introducing a model of hybrid photon. It seamlessly bridges the quantum
and the classical worlds. Photons are discrete energy packets only at the moment of
emission; then they evolve diffractively and propagate as classical waves. Thus,
"interference of a single indivisible photon" is only a non-causal assertion. We
demonstrate NIW with simple experiments.
Then, we apply IPM-Thinking to improve the photoelectric equation & we obtain
Non-Interaction of Wave (NIW) amplitudes. Note that Huygens explicitly articulated NIW by postulating his "secondary spherical wavelets". Later Fresnel
incorporated this postulate in the now famous Huygens-Fresnel (HF) diffraction integral. Most modern optical science and engineering are based upon propagating EM waves through optical devices and systems using this integral in some form or other. Maxwell's wave equation accepts HF integral as a solution.
Systematic application of IPM-T to our causal and working mathematical equations,
along with NIW in superposition experiments, reveal that Superposition Effects can
emerge only when the interacting material dipoles in a detector respond, whether
classically or quantum mechanically, to the joint stimulations due to all the
simultaneously superposed waves. This indicates the non-causality of our belief that
a single indivisible photon can interfere by itself. We would not have a causally
evolving universe had any stable elementary particle were to change itself through
self-interference. Further, our working superposition equations always contain two or more terms representing two or more independently evolving entities. That is why
we need physical instruments with two or more independent channels of propagation
along with appropriately placed detectors to generate physical superposition effects.
Nature does not violate causality. Otherwise, our causally framed equations would
not have been working so elegantly. -
Prof. Jie Wu, Westlake University, China, "Electronic nematicity in unconventional superconductors", Cancelled: Special Condensed Matter Physics Seminar2:00pm
11/21
Prof. Jie Wu, Westlake University, China, "Electronic nematicity in unconventional superconductors", Cancelled: Special Condensed Matter Physics Seminar
Thursday, November 21st, 2019
02:00 PM - 03:00 PM
Storrs Campus GS 119
Prof. Jie Wu, Westlake University, China
Electronic nematicity in unconventional superconductors
The mechanism of high temperature superconductivity is a long-standing mystery in condensed matter physics. Despite of the intensive efforts devoted to this topic since its discovery in 1987, the nature of the superconducting state and the normal state remains ambiguous. Starting from an unexpected observation that the voltage transverse to the current direction is not zero in high temperature superconductors (HTS), I will present our investigations for the underlying mechanism, which at the end leads to the picture of the spontaneous breaking of the rotational symmetry in the normal state of HTS. Such a peculiar state is named as the electronic nematic state, implying its origin is the electron-electron correlation and, more importantly, the motion of electrons is anisotropic in the Cu-O plane. This challenges the basics of the Fermi liquid theory that the electrons' motion is isotropic as the word "liquid" implies. By studying how the nematicity evolves with the temperature and the chemical doping, our experiments reach the conclusion that the high temperature superconductivity in fact emerges out of the electronic nematic state. Other unconventional superconductors, such as ruthenate and Fe-based superconductors, show very similar behavior, indicating the electronic nematicity may be deeply correlated with unconventional superconductivity.
I will also briefly discuss our findings of the dependence of the superconducting temperature on the superfluid density, the abnormal independence of the interface superconductivity on the chemical doping, and the charge cluster glass state in the vicinity of the superconductor-insulator transition. All these findings constitute a vague but coherent picture of HTS.
References:
1. J. Wu, A. T. Bollinger, X. He and I. Božović, "Spontaneous breaking of rotational symmetry in copper oxide superconductors", Nature 547, 432-435 (2017).
2. I. Božović, X. He, J. Wu and A. T. Bollinger, "Dependence of the critical temperature in overdoped copper oxides on superfluid density", Nature 536, 309-311 (2016).
3. J. Wu, A. T. Bollinger, J. Sun and I. Božović, "Hall effect in quantum critical charge cluster glass", Proc. Natl. Acad. Sci. USA 113, 4284-4289 (2016).
4. J. Wu, O. Pelleg, G. Logvenov, A. T. Bollinger, J. Sun, G. S. Boebinger, M. Vanević, Z. R adović and I. Božović, "Anomalous independence of interface superconductivity from carrier density", Nature Materials 12, 877-881 (2013). -
Dr. Christopher Faesi, University of Massachusetts Amherst, "The Forest AND the Trees: Bridging the multi-scale physics of star formation", Astronomy Seminar2:00pm
11/20
Dr. Christopher Faesi, University of Massachusetts Amherst, "The Forest AND the Trees: Bridging the multi-scale physics of star formation", Astronomy Seminar
Wednesday, November 20th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. Christopher Faesi, University of Massachusetts Amherst
The Forest AND the Trees: Bridging the multi-scale physics of star formation
The conversion of interstellar gas into stars provides the energy, momentum, and chemical enrichment that help drive the evolution of galaxies across cosmic time. Observational limitations have previously made it difficult to obtain a comprehensive understanding of the star formation process (and its role on environment) due to the large dynamic range in scales over which it is relevant. However pioneering new observational facilities are now moving the field from case studies to big data, enabling measurements across statistically significant samples of galaxies at very high resolution. This allows us for the first time to directly investigate how the small scale (< 100 pc) physics of star formation couples to large scale (1-10 kpc) galactic dynamics and environment.
I will highlight recent and ongoing progress, as part of a major international collaboration, toward a more complete picture of star formation in the local Universe. In particular, our large sample size enables the measurement and intercomparison of important physical quantities related to star formation including gas conversion efficiency, molecular cloud densities and dynamics, and star formation timescales across multiple galactic environments. Our ongoing campaigns will be even further augmented in the near future with the advent of the James Webb Space Telescope, which will provide arcsecond-scale imaging and spectroscopy of the near and mid-infrared, two critical spectral windows for accessing star formation-related physics. -
Dr. Cyril P. Opeil, Physics Department, Boston College , "Condensed Matter from Space: Thermal Properties of CM2 Meteorites", Condensed Matter Physics Seminar2:00pm
11/19
Dr. Cyril P. Opeil, Physics Department, Boston College , "Condensed Matter from Space: Thermal Properties of CM2 Meteorites", Condensed Matter Physics Seminar
Tuesday, November 19th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS 119
Dr. Cyril P. Opeil, Physics Department, Boston College
Condensed Matter from Space: Thermal Properties of CM2 Meteorites
Measurement of the low-temperature thermodynamic and physical properties of meteorites provides fundamental data for the study and understanding of asteroids and other small bodies. Of particular interest are the CM carbonaceous chondrites, which represent a class of primitive meteorites that record substantial chemical information concerning the evolution of the volatile-rich materials in the early solar system. Most CM chondrites contain both anhydrous minerals such as olivine and pyroxene, along with abundant hydrous phyllosilicates contained in the meteorite matrix interspersed between the chondrules. We have measured the thermal conductivity, heat capacity and thermal expansion of five CM carbonaceous chondrites (Murchison, Murray, Cold Bokkeveld, NWA 7309, Jbilet Winselwan) at low temperatures (5-300 K) that span the range of possible surface temperatures in the asteroid belt. The thermal expansion measurements show a substantial and unexpected decrease in CM volume as temperature decreases from 230 - 210 K followed by a gradual contraction below 210 K. Such transitions are not typical for other CV or CO carbonaceous chondrites. Thermal diffusivity and thermal inertia as a function of temperature are calculated from measurements of density, thermal conductivity and heat capacity. Our thermal diffusivity results compare well with previous estimates for similar meteorites, where conductivity was derived from diffusivity measurements and modeled heat capacities; our new values are of higher precision and cover a wider range of temperatures. -
Dr. William I. Jay, Theoretical Physics Department, Fermi National Accelerator Laboratory , "Composite BSM physics on the lattice", Particle, Astrophysics, and Nuclear Physics Seminar2:00pm
11/18
Dr. William I. Jay, Theoretical Physics Department, Fermi National Accelerator Laboratory , "Composite BSM physics on the lattice", Particle, Astrophysics, and Nuclear Physics Seminar
Monday, November 18th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-413E
Dr. William I. Jay, Theoretical Physics Department, Fermi National Accelerator Laboratory
Composite BSM physics on the lattice
My talk will describe recent results from lattice simulations of SU(4) gauge theory with simultaneous fermions in two different representations. The motivation for studying such a theory is twofold. First, this theory is closely related to a theory of physics beyond the Standard Model which was recently proposed in the literature. In this model, the Higgs boson is a composite particle, and the top quark is a partially composite particle. Second, theories of this sort represent a new direction in the study of gauge dynamics and thus provide many opportunities to test our qualitative understanding of strongly coupled physics. -
Prof. Zackaria Chacko, Department of Physics, University of Maryland, "Neutral Naturalness", Physics Colloquium (Prof. Zackaria Chacko, UMd)3:30pm
11/15
Prof. Zackaria Chacko, Department of Physics, University of Maryland, "Neutral Naturalness", Physics Colloquium (Prof. Zackaria Chacko, UMd)
Friday, November 15th, 2019
03:30 PM - 04:30 PM
Storrs Campus BPB-131
Prof. Zackaria Chacko, Department of Physics,
University of Maryland
Neutral Naturalness
I explain the hierarchy problem of the standard model of particle physics, and discuss some of the ideas which have been put forward to resolve it. I then show that a specific class of theories, built around a framework known as neutral naturalness, can help address this problem while remaining consistent with all current experimental tests. I explain that while certain theories in this class give rise to striking signals, others are extremely difficult to test, and require a detailed study of the properties of the Higgs boson. I consider the implications of these results for the Large Hadron Collider, and for future experimental programs.
Cookies will be served prior to the talk, at 3:00 p.m. outside BPB 131 -
Prof. E. Dormidontova, Department of Physics, University of Connecticut, "Soft Matter Physics: Computer Simulations and Theory", Graduate Student Seminar12:15pm
11/15
Prof. E. Dormidontova, Department of Physics, University of Connecticut, "Soft Matter Physics: Computer Simulations and Theory", Graduate Student Seminar
Friday, November 15th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. E. Dormidontova, Department of Physics, University of Connecticut
Soft Matter Physics: Computer Simulations and Theory
Soft matter has become an essential part of modern technology (including responsive and bio-mimicking materials, pharmaceutics, complex fluids, soft lithography, photonics, etc.). The physics of these materials is complex and diverse. I'll briefly introduce different areas of Soft Matter physics and discuss the specifics of behavior of these systems. The rich behavior of soft matter systems makes computer modeling especially desirable, as one can select the appropriate resolution level of the model and can test different analytical models or hypothesis by considering limits. I'll briefly introduce different computer modeling approaches that we use in my group and discuss several examples of recent work by my graduate students. I will also outline developing new projects, some in collaboration with experimental groups. I welcome questions and discussion during the seminar, so please do not hesitate to interrupt me and ask questions. -
23rd Annual Katzenstein Distinguished Lecture Series4:00pm
11/8
23rd Annual Katzenstein Distinguished Lecture Series
Friday, November 8th, 2019
04:00 PM - 05:00 PM
Storrs Campus Student Union Theater
Professor Dame Jocelyn Bell Burnell from the University of Oxford in England is world famous for her discovery of pulsars in 1967. At the time of the discovery of pulsars, Bell Burnell was a graduate student at the University of Cambridge and worked with her supervisor, Anthony Hewish. This discovery is considered one of the most important achievements of the 20th century and was recognized by a Nobel Prize in Physics in 1974, awarded to her supervisor Anthony Hewish as well as to astronomer Martin Ryle.
In 2018, she also received the Breakthrough Prize in Fundamental Physics. Bell Burnell donated her full $3 million Breakthrough prize to fund "women, underrepresented ethnic minority, and refugee students to become physics researchers." She told http://space.com, "I feel that I made my contribution in part because I felt an outsider," she added. "I was one of very few women, and I wasn't from the southeast of England, the affluent part of the country. So, I think increasing diversity of the workforce actually allows all sorts of things to develop."
Professor Dame Bell Burnell has a highly distinguished career including serving as the head of the Royal Astronomical Society, the first female president of both the Institute of Physics and The Royal Society of Edinburgh. For services to astronomy she was appointed Dame Commander of the Order of the British Empire by Her Majesty Queen Elizabeth II in 2007.
View the livestream at: https://www.youtube.com/TheUCTVchannel14 -
Prof. Meredith Hughes, Wesleyan, "Using Debris Disks to Trace the Dynamics of Planetary Systems", Physics Colloquium (Prof. Meredith Hughes, Wesleyan)3:30pm
11/1
Prof. Meredith Hughes, Wesleyan, "Using Debris Disks to Trace the Dynamics of Planetary Systems", Physics Colloquium (Prof. Meredith Hughes, Wesleyan)
Friday, November 1st, 2019
03:30 PM - 04:30 PM
Storrs Campus BPB 131
Prof. Meredith Hughes, Wesleyan
Using Debris Disks to Trace the Dynamics of Planetary Systems
Debris disks are signposts of mature planetary systems, and millimeter-size dust is an excellent tracer of the gravitational landscape around planets. I will describe observations using the Atacama Large Millimeter/Submillimeter Array (ALMA) that leverage the presence of debris disks to explore the dynamics of planetary systems. For example, we can use the vertical puffiness (or lack thereof) to hunt for otherwise invisible Uranus and Neptune analogs, and in systems with directly imaged companions we can use the chaotic zone extent as a measurement of the dynamical mass of the companion. We are also using millimeter disk morphology as a test of theories of the origin of wide-separation planets.
Cookies will be served prior to the talk, at 3:00 p.m. outside BPB-131 -
Prof. C. Battersby, Department of Physics, University of Connecticut, "The Milky Way Laboratory", Graduate Student Seminar12:15pm
11/1
Prof. C. Battersby, Department of Physics, University of Connecticut, "The Milky Way Laboratory", Graduate Student Seminar
Friday, November 1st, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. C. Battersby, Department of Physics, University of Connecticut
The Milky Way Laboratory
Our own Milky Way Galaxy is a powerful and relatively nearby laboratory in which to study the physical processes that occur throughout the Universe. From the organization of gas on galactic scales to the life cycle of gas and stars under varied environmental conditions, studies of our Milky Way underpin many areas of modern astrophysics. I will present a brief tour of our Milky Way Laboratory, including 1) the connection between long, filamentary molecular clouds and spiral structure, and 2) how observing our extreme, turbulent Galactic Center (the Central Molecular Zone) can help us learn more about how gas is converted into stars during the peak epoch of cosmic star formation. I will also briefly discuss the Origins Space Telescope, a NASA mission concept study for the 2020 Decadal survey, opening up about 3 orders of magnitude of discovery space on science from first stars to life.
Nuclear Astrophysics -
H. Perry Hatchfield, Department of Physics, University of Connecticut, "Understanding Enigmatic Star Formation Activity in the Milky Way's Galactic Center", Astronomy Seminar2:30pm
10/30
H. Perry Hatchfield, Department of Physics, University of Connecticut, "Understanding Enigmatic Star Formation Activity in the Milky Way's Galactic Center", Astronomy Seminar
Wednesday, October 30th, 2019
02:30 PM - 03:00 PM
Storrs Campus GS-119
H. Perry Hatchfield, Department of Physics, University of Connecticut
Understanding Enigmatic Star Formation Activity in the Milky Way's Galactic Center
The CMZoom Survey, a Submillimeter Array (SMA) large program, has produced a catalog of dense objects in the 1.3mm dust continuum, complete within all high (\(>10^{23}\) N(H2)) column density clouds across the inner 300 pc of the Milky Way. This region, known as the Central Molecular Zone (CMZ) is well studied for its extreme densities, pressures, temperatures and turbulent forces relative to the Galactic disk, as well as a mysterious deficiency of star formation relative to its dense molecular gas content. To understand this deficiency, we are building a suite of hydrodynamic simulations with a consistent dynamical model for the CMZ, implemented with variable physics. By developing these simulations and observations together, we aim to compile a set of tools to better understand the relationship between dense gas and star formation across galactic environments. -
Gloria Fonseca Alvarez, Department of Physics, University of Connecticut, "The Sloan Digital Sky Survey Reverberation Mapping Project Radius Luminosity Relation", Astronomy Seminar2:00pm
10/30
Gloria Fonseca Alvarez, Department of Physics, University of Connecticut, "The Sloan Digital Sky Survey Reverberation Mapping Project Radius Luminosity Relation", Astronomy Seminar
Wednesday, October 30th, 2019
02:00 PM - 02:30 PM
Storrs Campus GS-119
Gloria Fonseca Alvarez, Department of Physics, University of Connecticut
The Sloan Digital Sky Survey Reverberation Mapping Project Radius Luminosity Relation
Results from a few decades of reverberation mapping (RM) studies have revealed a correlation between the radius of the broad-line emitting region and the continuum luminosity of active galactic nuclei. This "radius-luminosity" relation allows us to estimate black-hole masses across cosmic time, using single-epoch spectroscopy rather than long-term RM monitoring.
I will discuss results from the Sloan Digital Sky Survey Reverberation Mapping project that differ significantly from the previously established radius-luminosity relation, introducing new challenges for single-epoch black hole masses. -
Dr. Leonid Glazman, Department of Physics, Yale University, "Topology of the Fermi surface wave functions and magnetic oscillations in metals", Condensed Matter Physics Seminar2:00pm
10/29
Dr. Leonid Glazman, Department of Physics, Yale University, "Topology of the Fermi surface wave functions and magnetic oscillations in metals", Condensed Matter Physics Seminar
Tuesday, October 29th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS 119
Dr. Leonid Glazman,
Department of Physics, Yale University
Topology of the Fermi surface wave functions and magnetic oscillations in metals
In the traditional Fermiology, the size and shape of the Fermi surface in a metal is often deduced from the period of magnetic oscillations of transport or thermodynamic characteristics, e.g., from the de Haas -- van Alphen effect. We find that the intercept g of the infinite-field asymptote of the oscillations yields information about the topology of the Fermi surface wave functions. The topological invariance of g originates from the symmetry of extremal orbits, which depends not only on the space group but also on the field orientation with respect to the crystal axes. The wave functions fall into 10 distinct classes stemming from the crystalline symmetry; transitions between the classes occur via magnetic breakdown. -
Prof. Chunlei Guo, Department of Physics and Astronomy, University of Rochester, "Material Functionalization with Femtosecond Lasers", Physics Colloquium (Prof. Chunlei Guo, University of Rochester)3:30pm
10/25
Prof. Chunlei Guo, Department of Physics and Astronomy, University of Rochester, "Material Functionalization with Femtosecond Lasers", Physics Colloquium (Prof. Chunlei Guo, University of Rochester)
Friday, October 25th, 2019
03:30 PM - 04:30 PM
Storrs Campus BPB-131
Prof. Chunlei Guo, Department of Physics and Astronomy, University of Rochester
Material Functionalization with Femtosecond Lasers
Femtosecond lasers are a powerful tool for high-precision material processing and functionalization. In this talk, I will discuss some of our recent advancements in femtosecond laser micro- and nano-processing, including the resulting surface structures, their formation dynamics, the drastically altered surface functionalities, and demonstration of various applications. I will also discuss the broader research activities in my labs, including extreme nonlinear optics, advanced material development, nanophotonics, and ultrafast metrology.
Cookies will be served prior to the talk, at 3:00PM outside Room BPB-131 -
Prof. M. Gai, Department of Physics, University of Connecticut, "Nuclear Astrophysics", Graduate Student Seminar12:15pm
10/25
Prof. M. Gai, Department of Physics, University of Connecticut, "Nuclear Astrophysics", Graduate Student Seminar
Friday, October 25th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. M. Gai, Department of Physics, University of Connecticut
Nuclear Astrophysics
Stellar evolution and Cosmological processes (after the first three minutes) are for the most part, nuclear processes. Nuclear Astrophysics, the study of these processes, reached a level of maturity where Stars and Cosmological events can be used to study fundamental questions in Physics. We will review some of these processes as an introduction to Nuclear Astrophysics, where stars have been used to study neutrino properties and deviation from the standard model. I will review a few of these questions that were studied at the Laboratory for Nuclear Science (LNS) at Avery Point together with an emphasis on open questions that are now being addressed at the LNS. -
Dr. C. Vargas, Department of Astronomy and Steward Observatory, University of Arizona, "Disk-halo interaction in nearby galaxies -- New SFRs and the bright (but low surface brightness) future of UV space astronomy", Astronomy Seminar2:00pm
10/23
Dr. C. Vargas, Department of Astronomy and Steward Observatory, University of Arizona, "Disk-halo interaction in nearby galaxies -- New SFRs and the bright (but low surface brightness) future of UV space astronomy", Astronomy Seminar
Wednesday, October 23rd, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. C. Vargas, Department of Astronomy and Steward Observatory, University of Arizona
Disk-halo interaction in nearby galaxies -- New SFRs and the bright (but low surface brightness) future of UV space astronomy
I present current efforts and future ultraviolet (UV) space missions aimed at determining the nature of disk-halo interactions and star formation in the nearby universe. I discuss new narrow-band H-alpha imaging for 24 nearby edge-on galaxies in the Continuum Halos in Nearby Galaxies -- an EVLA Survey (CHANG-ES). I use the images in conjunction with the Wide-field Infrared Survey Explorer 22 micron imaging of the sample to estimate improved star formation rates (SFRs) using the updated recipe from Vargas et al. (2018). I will discuss new observational evidence for the use of a mid-IR extinction correction applied to SFR calibrations when used in edge-on or extremely dusty galaxies. The revised SFR estimates produce a newly-measured correlation between SFR and radio scale height, and further relationships between star formation and radio halo properties are explored. I identify a region of star formation located at extreme distance from the disk of NGC 4157, possibly ionized by a single O5.5 V star.
In the second part of this talk, I will discuss future UV space mission concepts currently being developed at the University of Arizona. The Hyperion Small Explorer mission (P.I., E. Hamden) will directly measure molecular hydrogen through its fluorescent line transitions in the UV. The main goals of Hyperion are to understand the behavior of molecular clouds at their surfaces, test cloud lifecycle theories, and understand the impact of cloud surface conditions on their interiors. Lastly, I will discuss a SmallSat concept (P.I., C. Vargas) that will map the elusive coronal gas phase in nearby galaxy halos via the O VI transition in the Far-UV. Both of these missions are enabled by major recent advancements in UV coatings and detector technology. -
Prof. P. Mannheim and Prof. J. Trump , Physics Colloquium (The 2019 Nobel Prize in Physics)3:30pm
10/18
Prof. P. Mannheim and Prof. J. Trump , Physics Colloquium (The 2019 Nobel Prize in Physics)
Friday, October 18th, 2019
03:30 PM - 04:30 PM
Storrs Campus BPB-131
Prof. P. Mannheim and
Prof. J. Trump
The 2019 Nobel Prize in Physics
The 2019 Nobel Prize in physics was awarded to James Peebles for cosmology, and to Michel Mayor and Didier Queloz for the discovery of exoplanets. This colloquium will describe their work. -
Prof. A. Puckett, Department of Physics, University of Connecticut, "Sub-femtoscale structure of strongly interacting matter from "hard" electron-nucleus collisions", Graduate Student Seminar12:15pm
10/18
Prof. A. Puckett, Department of Physics, University of Connecticut, "Sub-femtoscale structure of strongly interacting matter from "hard" electron-nucleus collisions", Graduate Student Seminar
Friday, October 18th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. A. Puckett, Department of Physics, University of Connecticut
Sub-femtoscale structure of strongly interacting matter from "hard" electron-nucleus collisions
The emergence of nucleon structure and dynamics from strong interactions among its elementary quark and gluon constituents is one of the most difficult and interesting problems in all of physics. The strong interaction, NOT the electroweak Higgs mechanism, is responsible for the dynamical generation of the mass of approximately 98% of all ordinary matter in the universe. Scattering of ultrarelativistic electron beams from nucleon and nuclear targets is the tool of choice for the precision study of nucleon structure.
The Super BigBite Spectrometer (SBS) at Jefferson Lab, a novel device currently nearing completion, with installation and first beam tentatively scheduled for 2020, will facilitate a focused program of high-impact nucleon structure measurements in electron-nucleon scattering at large momentum transfer. In this talk I will give an overview of the SBS program and opportunities for graduate student involvement. -
Dr. V. Juričić, Nordic Institute for Theoretical Physics, "Higher order topological states: General principle of construction and their realizations", Condensed Matter Physics Seminar2:00pm
10/17
Dr. V. Juričić, Nordic Institute for Theoretical Physics, "Higher order topological states: General principle of construction and their realizations", Condensed Matter Physics Seminar
Thursday, October 17th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. V. Juričić,
Nordic Institute for Theoretical Physics
Higher order topological states: General principle of construction and their realizations
Topological gapless edge or surface states are protected by the bulk topological invariant and arise as a consequence of the so-called bulk-boundary correspondence, which is a hallmark feature of a topological state. Recently, the notion of topological states of matter has been extended to the so-called higher order topological (HOT) states featuring gapless surface states at boundaries of co-dimension higher than one, such as hinges and corners.
In this talk, I will particularly discuss a general principle of construction for these states within the Dirac Hamiltonian framework [1]. As I will show, if a D-dimensional first-order or regular topological phase involves m Hermitian matrices that anticommute with additional p−1 mutually anticommuting matrices, it is conceivable to realize an nth-order HOT phase, where n=1,...,p, with appropriate combinations of discrete symmetry-breaking Wilsonian masses. This principle will be illustrated on prototypical three-dimensional gapless systems, such as a nodal-loop semimetal possessing SU(2) spin-rotational symmetry, and Dirac semimetals, transforming under (pseudo)spin- 1/2 or 1 representations. The former system permits an unprecedented realization of a fourth-order phase, without any surface zero modes. The crystalline symmetries play an important for HOT states, but, as I will show, they can also be realized in amorphous solids [2]. Particularly, as long as structural disorder is confined by the outer crystalline boundary, the system continues to host corner states, realizing an amorphous HOT insulator. However, as structural disorder percolates to the edges, corner states start to dissolve into amorphous bulk, and ultimately the system becomes a trivial insulator. Finally, I will discuss a realization of an out-of-equilibrium second order topological insulator, which is obtained from a quantum spin Hall insulator by using a rather generic kicking protocol involving a mass that breaks time-reversal and fourfold rotational symmetries [3].
1. D. Calugaru, V. Juričić, and B. Roy, Phys. Rev. B 99, 041301(R) (2019).
2. A. Agarwala, V. Juričić, and B. Roy, B., arXiv:1902.00507.
3. T. Nag, V. Juričić, and B. Roy, arXiv:1904.07247. -
Dr. Jian-Xin Zhu, Los Alamos National Laboratory, "Electronic Structure and Topology in f-Electron Quantum Matter", Condensed Matter Physics Seminar2:00pm
10/15
Dr. Jian-Xin Zhu, Los Alamos National Laboratory, "Electronic Structure and Topology in f-Electron Quantum Matter", Condensed Matter Physics Seminar
Tuesday, October 15th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. Jian-Xin Zhu, Los Alamos National Laboratory
Electronic Structure and Topology in f-Electron Quantum Matter
In recent years there has been a surge of interest in quantum materials with topologically protected properties, which are robust against disorder effects. Interesting examples are topological insulators and three-dimensional Weyl metals. Electronic structure has played an important role in the exotic properties of these materials. In this talk, I will present our recent theoretical study of electronic structure and its topology in f-electron PuB\({}_4\) [1] and Ce\({}_3\)(Pt,Pd)\({}_3\)Bi\({}_4\) [2] compounds. In addition to uncovering topologically nontrivial electronic states, the role of f-electron and in particular the electronic correlation effects are discussed in the framework of density functional theory and its combination with the dynamical mean-field theory.
[1] H. Choi, W. Zhu, S.K. Cary, L.E. Winter, Z. Huang, R.D. McDonald, V. Mocko, B.L. Scott, P.H. Tobash, J.D. Thompson, S.A. Kozimor, E.D. Bauer, J.-X. Zhu, and F. Ronning, "Experimental and theoretical study of topology and electronic correlations in PuB\({}_4\)", Phys. Rev. B 97, 201114(R) (2018).
[2] C. Cao, G.-X. Zhi, and J.-X. Zhu, "From Trivial Kondo Insulator Ce\({}_3\)Pt\({}_3\)Bi\({}_4\) to Topological Nodal-line Semimetal Ce\({}_3\)Pd\({}_3\)Bi\({}_4\)", arXiv:1904.00675. -
Dr. Masakaki Tomii, Department of Physics, University of Connecticut Non-perturbative matching of Wilson coefficients from four-flavor to three-flavor theories using lattice QCD, Particle, Astrophysics, and Nuclear Physics Seminar2:00pm
10/14
Dr. Masakaki Tomii, Department of Physics, University of Connecticut Non-perturbative matching of Wilson coefficients from four-flavor to three-flavor theories using lattice QCD, Particle, Astrophysics, and Nuclear Physics Seminar
Monday, October 14th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-413.E
Dr. Masakaki Tomii, Department of Physics, University of Connecticut
Non-perturbative matching of Wilson coefficients from four-flavor to three-flavor theories using lattice QCD
The first lattice result for direct CP violation in \(K \to \pi\pi\) decay in the Standard Model published by RBC/UKQCD in 2015 is desired to be more precise to see the deviation from the experimental value more clearly. In this talk, I will overview RBC/UKQCD's calculation of \(K \to \pi\pi\) matrix elements mentioning a particular error
source: Since RBC/UKQCD calculated the matrix elements with the four-quark operators without the charm quark, we need the
corresponding Wilson coefficients in the three-flavor theory, which can be obtained by converting from the four-flavor theory.
Perturbative matching may result in a significant uncertainty since it
needs to be done below charm threshold. To resolve this problem, we are trying to do this matching in a non-perturbative prescription using lattice QCD. I will explain the strategy of the matching and show some results of an exploratory calculation. -
Dr. Jianwei Qiu, Director, Theory Center, Jefferson Lab, "Nuclear Femtography - A new frontier of science and technology", Physics Colloquium3:30pm
10/11
Dr. Jianwei Qiu, Director, Theory Center, Jefferson Lab, "Nuclear Femtography - A new frontier of science and technology", Physics Colloquium
Friday, October 11th, 2019
03:30 PM - 04:30 PM
Storrs Campus BPB 131
Dr. Jianwei Qiu, Director, Theory Center, Jefferson Lab
Nuclear Femtography - A new frontier of science and technology
The proton and neutron, known as nucleons, are the fundamental building blocks of all atomic nuclei and make up essentially all the visible matter in the universe, including the stars, the planets, and us. Nucleons are not static but have complex internal structure, emerged as strongly interacting and relativistic bound states of quarks and gluons of Quantum Chromodynamics. Both theory and experimental technology have now reached a point where human is capable of exploring the inner structure of nucleons and nuclei at a sub-femtometer without breaking them, which is expected to lead to a new emerging science of nuclear femtography. In this talk, I will demonstrate that as exciting as the nano-science and technology has been for recent years, there must be a quantum transition when we enter the era of femto-science and technology. The newly upgraded CEBAF facility at Jefferson Lab and proposed Electron-Ion Collider to be built in the US will be a pair of complementary and much needed facilities for exploring the nuclear femtography. They are the most powerful tomographic scanners and/or microscopes able to precisely image inner structure of nucleon and nuclei with a sub-femtometer resolution to help address the most compelling unanswered questions about the elementary building blocks of the visible world, and are capable of taking us to the next frontier of the Standard Model of physics. -
Prof. George N. Gibson, High-Intensity Laser Physics Group, Department of Physics, University of Connecticut, "Exploring Extreme Nonlinear Physics and Quantum Molecular Dynamics with High-Intensity Laser Pulses", Graduate Student Seminar12:15pm
10/11
Prof. George N. Gibson, High-Intensity Laser Physics Group, Department of Physics, University of Connecticut, "Exploring Extreme Nonlinear Physics and Quantum Molecular Dynamics with High-Intensity Laser Pulses", Graduate Student Seminar
Friday, October 11th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. George N. Gibson, High-Intensity Laser Physics Group, Department of Physics, University of Connecticut
Exploring Extreme Nonlinear Physics and Quantum Molecular Dynamics with High-Intensity Laser Pulses
Ultrafast laser systems can now produce ultrashort (attosecond) pulses of light with extremely high intensity (\(10^{22}\) W/\(cm^2\)), as recognized by the 2018 Nobel Prize in Physics. This has opened up a new world in nonlinear physics and may even test the nonlinear polarizability of the vacuum, itself. More immediate applications may include direct imaging of molecular orbitals and ultrafast atomic scale dynamics. -
Philip Engelke, Department of Physics and Astronomy, Johns Hopkins University, "OH as an Alternate Tracer for Molecular Gas", Astronomy Seminar2:00pm
10/9
Philip Engelke, Department of Physics and Astronomy, Johns Hopkins University, "OH as an Alternate Tracer for Molecular Gas", Astronomy Seminar
Wednesday, October 9th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Philip Engelke,
Department of Physics and Astronomy, Johns Hopkins University
OH as an Alternate Tracer for Molecular Gas
While molecular gas is an important component of the baryonic mass content of galaxies, tracing interstellar molecular H2 gas is complicated by the fact that diffuse, cold H2 is not detectable. In order to study the mass and distribution of molecular gas in galaxies, tracers such as CO are typically used as surrogates. Evidence suggests large reservoirs of undetected "CO-dark" molecular gas. In this work, we explore the use of OH 18 cm transition as an alternate tracer for molecular gas, by performing observational surveys with the Green Bank Telescope. OH appears to be a viable tracer, and reveals molecular gas in places where CO has not been detected. This finding indicates a larger extent and mass of molecular gas in the Galaxy, translating to roughly twice the known mass of H2. I will describe our results for a "blind survey", as well as a study of the W5 star-forming region in comparison to quiescent interstellar regions, and modeling of the volume density in these different regions. We find that CO-dark molecular gas is widespread and predominantly located outside of star-forming regions, the more typical targets of astronomical observation, and occurs in regions of lower volume density gas. I also describe a technique making use of measured differences in OH main line excitation temperatures and modeling to probe physical conditions of molecular gas. -
Dr. Seok-Woo Lee, Materials Science and Engineering, University of Connecticut, "Superelasticity of ThCr2Si2-Structured Intermetallic Compounds at the Micrometer Scale", Condensed Matter Physics Seminar2:00pm
10/8
Dr. Seok-Woo Lee, Materials Science and Engineering, University of Connecticut, "Superelasticity of ThCr2Si2-Structured Intermetallic Compounds at the Micrometer Scale", Condensed Matter Physics Seminar
Tuesday, October 8th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. Seok-Woo Lee, Materials Science and Engineering, University of Connecticut
Superelasticity of ThCr2Si2-Structured Intermetallic Compounds at the Micrometer Scale
The work represents a report of the discovery of superelasticity in ThCr2Si2-structured novel intermetallic compound (CaFe2As2) and its hybrid structure (CaKFe4As4) under "uni-axial" compression at the micrometer scale and discusses the strong possibility of deformation-induced superconductivity switching. They exhibit unprecedentedly large elastic limit (10~17%), ultrahigh strength (3~5 GPa), and repeatable cyclic loading response through the reversible lattice collapse caused by making and breaking atomic bonds.1-4 This unique superelasticity mechanism produces a modulus of resilience orders of magnitude higher than that of most engineering materials and enables strain engineering, which refers to the modification of material properties through elastic strain. Our experimental and computational results strongly suggest that superconductivity in a high temperature superconductor, CaKFe4As4, could be turned on/off reliably through this superelasticity process, before fracture occurs, even under "uniaxial" compression. Please note that it is extremely rare to see deformation-induced superconductivity switching under uni-axial deformation, which is the preferred loading mode in engineering applications. Note that our result is only one manifestation of a wider class of such transitions found in over 2500 different ThCr2Si2-structured intermetallic compounds. If we consider their hybrid structure, there could be a much larger number of similar intermetallic compounds. Therefore, our observation can be extended to search for a large group of superelastic and strain-engineerable functional materials, and, more broadly, will lead to various research opportunities in materials science, solid-state physics, superconducting device engineering, and machine-learning-based materials research.
1. J.T. Sypek, C.R. Weinberger, S. Vijayan, M. Aindow, P.C. Canfield, S.-W. Lee, Scripta Mater. 141 10 (2017)
2. J.T. Sypek, H. Yu, K.J. Dusoe, G. Drachuck, H. Petal, A.M. Giroux, A.I. Goldman, A. Kreyssig, P.C. Canfield, S.L. Bud'ko, C.R. Weinberger, S.-W. Lee, Nature Comm. 8 1083 (2017)
3. I.N. Bakst, J.T. Sypek, S.-W. Lee, J.R. Neilson, C.R. Weinberger, -- Comp. Mater. Sci. 150, 86 (2018)
4. I.N. Bakst, K.J. Dusoe, G. Drachuk, J.R. Neilson, P.C. Canfield, S.-W. Lee, C.R. Weinberger, Acta Mater. 160 224 (2018) -
Dr. George C. Privon, Department of Astronomy, University of Florida, "Gas as a Tracer and Driver of Galaxy Evolution", Physics Colloquium3:30pm
10/4
Dr. George C. Privon, Department of Astronomy, University of Florida, "Gas as a Tracer and Driver of Galaxy Evolution", Physics Colloquium
Friday, October 4th, 2019
03:30 PM - 04:30 PM
Storrs Campus BPB 131
Dr. George C. Privon,
Department of Astronomy,
University of Florida
Gas as a Tracer and Driver of Galaxy Evolution
Nearby galaxies exhibit a diverse range of properties, from low-metallicity star-forming dwarfs through the merger-triggered compact starbursts in ultraluminous infrared galaxies. This provides a variety of laboratories to probe the physics of star formation across a wide range of physical conditions. Molecular and atomic interstellar medium (ISM) tracers probe the conditions of star forming gas as well as the impact star formation has on its surroundings. Understanding the physical drivers of emission from these ISM tracers is thus critical to understanding the physics of star formation. I will discuss our understanding of so called "dense gas" tracers in starburst galaxies and how these can probe the physical conditions of star formation. I will also describe an optical integral field spectroscopy program on dwarf galaxy pairs aimed at understanding how hierarchical formation drives star formation in low-metallicity, high gas fraction systems. Finally, I will describe ongoing efforts to leverage detailed galaxy evolution simulations to make direct comparisons with observations; applications include interpretation of ISM tracers as well as age-dating galaxy mergers and constraining their dynamical evolution. These studies provide new insights into the interpretation of molecular gas tracers and signs of intriguing behavior in merger-driven starbursts within high gas fraction galaxies.
Cookies will be served prior to the talk, at 3:00 p.m. in Room Gant South 117 -
Prof. Jonathan Trump, Department of Physics, University of Connecticut, "Multi-Messenger Echoes of Supermassive Black Holes", Graduate Student Seminar12:15pm
10/4
Prof. Jonathan Trump, Department of Physics, University of Connecticut, "Multi-Messenger Echoes of Supermassive Black Holes", Graduate Student Seminar
Friday, October 4th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. Jonathan Trump, Department of Physics, University of Connecticut
Multi-Messenger Echoes of Supermassive Black Holes
Our new era of gravitational wave astrophysics has opened an entirely new frontier for understanding black holes, from their birth in the early Universe to the supermassive monsters observed in all massive galaxies today. I will demonstrate how a new generation of industrial-scale time-domain surveys is creating a new multi-messenger view of supermassive black holes. The pioneering new SDSS-RM project uses light echoes to map the three fundamental quantities that describe astrophysical black holes: mass, spin, and growth rate. In the next decade, the new SDSS-V Black Hole Mapper and Large Synoptic Survey Telescope will map millions of supermassive black holes in light echoes, complementing the gravitational echoes seen soon in pulsar timing and (eventually) LISA. I will also discuss how Hubble Space Telescope spectroscopy can spatially resolve the fossil record of black hole seeds, as well as off-nuclear black holes leftover from recent galaxy mergers. Very soon, the first James Webb Space Telescope observations in the CEERS project will directly map the formation of the first black hole seeds in the early Universe. The next generation of multi-messenger experiments make it a truly bright time for understanding the dark nature of black hole astrophysics. -
Prof. Michael Lublinsky, Department of Physics, Ben-Gurion University, "Transport from the Fluid/Gravity Correspondence", Particle, Astrophysics, and Nuclear Physics Seminar2:00pm
10/2
Prof. Michael Lublinsky, Department of Physics, Ben-Gurion University, "Transport from the Fluid/Gravity Correspondence", Particle, Astrophysics, and Nuclear Physics Seminar
Wednesday, October 2nd, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-413.E
Prof. Michael Lublinsky, Department of Physics, Ben-Gurion University
Transport from the Fluid/Gravity Correspondence
I will first review the ideas behind all order causal relativistic hydrodynamics. Then, such hydrodynamics will demonstrated to emerge from the AdS/CFT. Finally, I will talk about chiral anomaly induced transport. -
C. Trallero-Giner, Latin-American Center of Physics, Rio de Janeiro, Brazil, "Latin American Center for Physics, a challenge for the developing of science", Physics Colloquium3:30pm
9/27
C. Trallero-Giner, Latin-American Center of Physics, Rio de Janeiro, Brazil, "Latin American Center for Physics, a challenge for the developing of science", Physics Colloquium
Friday, September 27th, 2019
03:30 PM - 04:30 PM
Storrs Campus BPB-131
C. Trallero-Giner, Latin-American Center of Physics, Rio de Janeiro, Brazil
Latin American Center for Physics, a challenge for the developing of science
Latin American Center for Physic (CLAF) has the unique status among other Latin American institutions of being an intergovernmental organization. There is no such thing for mathematics, chemistry or other discipline. The representatives at CLAF are in fact representatives of the country member states. Due to its official status, it represents an opportunity to find a way for the developing of sciences in Latin America region.
Latin American cultural history and its link with the scientific development is presented. The present talk presents an analysis of the development of science and technology in the region and the new paradigms that such Center has to face. The fields highly developed in the region are also presented and discussed.
The contributions of the organism, its distinctive feature, the different types of graduate staff training and links with various bodies that keeps the CLAF currently listed. The projection center programs to Latin America and Central America are presented emphasizing support for experimental research and technological development. The search of joint scientific policies among various similar bodies to CLAF is important for achieving new paradigms
that allow more rapid development of science and technology in Latin America.
Please join us for the Fall Ice Cream Social hosted by the Physics Graduate Student Association (PGSA) at 1:30PM in GS117 -
Prof. V. Cormier, Department of Physics, University of Connecticut, "Scattered Elastic Waves Reveal Small-scale Planetary Structure", Graduate Student Seminar12:15pm
9/27
Prof. V. Cormier, Department of Physics, University of Connecticut, "Scattered Elastic Waves Reveal Small-scale Planetary Structure", Graduate Student Seminar
Friday, September 27th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. V. Cormier, Department of Physics, University of Connecticut
Scattered Elastic Waves Reveal Small-scale Planetary Structure
Planetary structures on the order of a wavelength (1-10 km) of the elastic waves radiated by earthquakes have observable and predictable effects on recorded seismograms expressed as energy scattered into different directions and time windows. I will describe two applications that exploit observations of the scattered seismic wavefield to determine the heterogeneity spectrum of Earth's deep interior. Small-scale structures in Earth's mantle affects the coherence of seismic body waves recorded by surface arrays of seismometers through focusing, defocusing, and scattering. In one application, we are extending theories of forward wave scattering to invert the amplitude and travel time coherence of seismic waves to reveal the solid-solid phase changes predicted for the lattices of silicate minerals composing Earth's mantle. In another application, we use a radiative transport theory to show how the heterogeneity spectrum and variations in the thickness of Earth's crust can affect the amplitude of S body waves trapped in a crustal waveguide. These crust-trapped S waves are better excited by earthquakes than explosions; hence are useful for nuclear test monitoring, but are sometimes blocked by crustal thickness variations. -
Dr. Jacqueline McCleary, NASA Jet Propulsion Laboratory, Pasadena, CA, "Dark Matter and Galactic Dust at Megaparsec Scales", Astronomy Seminar2:00pm
9/25
Dr. Jacqueline McCleary, NASA Jet Propulsion Laboratory, Pasadena, CA, "Dark Matter and Galactic Dust at Megaparsec Scales", Astronomy Seminar
Wednesday, September 25th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. Jacqueline McCleary, NASA Jet Propulsion Laboratory, Pasadena, CA
Dark Matter and Galactic Dust at Megaparsec Scales
Though it comprises 80% of gravitationally interacting matter, the exact nature of dark matter is still unknown. As the largest virialized objects in the universe, clusters of galaxies lie at the nexus of cosmology and astrophysics and make excellent test beds for theories of dark matter. In this talk, I will discuss our survey of substructures in the dark matter of massive, nearby, clusters of galaxies. We reconstruct these clusters' mass distributions through their weak gravitational lensing signal, the small but coherent distortion they induce on the shapes of galaxies in their backgrounds.
Cluster cosmology studies like our own require accurate galaxy colors, and in this context I will also present evidence for an anomalous, extended, halo of dust around galaxies. By correlating the reddening of light from background galaxies with the locations of foreground objects, we find evidence of dust extending out to 10 Mpc. This potentially major systematic error is not currently accounted for in cluster cosmology studies. -
Prof. D. McCarron, Department of Physics, University of Connecticut, Graduate Student Seminar12:15pm
9/20
Prof. D. McCarron, Department of Physics, University of Connecticut, Graduate Student Seminar
Friday, September 20th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. D. McCarron, Department of Physics, University of Connecticut
Laser-cooled molecules for quantum science and ultracold chemistry
Molecular laser cooling and trapping offers a general technique to produce ultracold molecules and is applicable to a variety of species with different internal structures. This generality is well-suited to the growing list of proposed applications for ultracold molecules, from time-resolved quantum simulations to ultracold organic chemistry. However, current limitations prevent the detection and manipulation of the necessary molecule-molecule interactions in laser-cooled samples. The key barrier is inefficient trap loading, which limits the densities achieved in molecular magneto-optical traps. Here we describe two complementary experiments designed to remove this barrier and realize large, dense samples of ultracold molecules. The first targets polar molecules with closed electronic shells, such as AlCl, which have strong optical transitions ideal for trap loading and weak transitions for laser cooling towards 1 μK. The second targets light, chemically relevant species with blue optical transitions such as CH and CN. These species can give access to increased optical forces and short slowing distances thanks to their high recoil velocities. We will discuss the advantages and challenges associated with laser cooling these new species and present an update on our experimental progress. -
Dr. Michael Mattern,Max Planck Institute for Radio Astronomy, Germany, "Massive filamentary clouds and their role in star formation", Astronomy Seminar2:00pm
9/18
Dr. Michael Mattern,Max Planck Institute for Radio Astronomy, Germany, "Massive filamentary clouds and their role in star formation", Astronomy Seminar
Wednesday, September 18th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. Michael Mattern,Max Planck Institute for Radio Astronomy, Germany
Massive filamentary clouds and their role in star formation
Filamentary structures are ubiquitous in the interstellar medium of the Milky Way. They are observed within star-forming and quiescent molecular clouds and representing molecular clouds themselves. Therefore, filamentary structures play an important role in the early phases of star formation. Filaments in nearby (<500pc) molecular clouds were found to be thermally stable against gravitational collapse, fragmenting into star-forming clumps. However, the evolution of filaments with masses above the thermally critical value is unknown.
Here, I will present the analyzes of the kinematics of 283 filamentary molecular cloud candidates in the Galactic Plane using the 13CO(2--1) and C18O(2--1) data of the SEDIGISM (Structure, Excitation, and Dynamics of the Inner Galactic Inter Stellar Medium) survey. To do so, we developed an automated algorithm to derive size, mass, and kinematic properties towards all candidates. We find two-third of the filament candidates are coherent structures. Also, we find a correlation between the mass per unit length and the velocity dispersion of the filament.
Further, I present the fragmentation characteristics and kinematics of the extremely long, massive Nessie filament. The fragmentation characteristics are derived from a combined near- and mid-infrared dust extinction map, and then compared with predictions from gravitational fragmentation models. We find that the characteristics of the fragments at all scales are similar to the predictions of one model. The kinematics provided by the SEDIGISM survey reveal Nessie as a single physical object, despite several morphological differences along the filament. -
Prof. P. Mannheim, Department of Physics, University of Connecticut, "Quantum mechanics off the beaten track", Graduate Student Seminar12:15pm
9/13
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Prof. P. Mannheim, Department of Physics, University of Connecticut, "Quantum mechanics off the beaten track", Graduate Student Seminar
Friday, September 13th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. P. Mannheim, Department of Physics, University of Connecticut
Quantum mechanics off the beaten track
We discuss some non-conventional options for quantum theory. We show that
it is not always possible to write the momentum operator as the familiar derivative operator \(-id/dx\) where x is real, and discuss what one should then do. We show that basis states do not need to be normalizable to be complete, and even if normalizable do not have to obey the standard Dirac
completeness relation \(\sum |n> Prof. B. Spivak, Department of Physics, University of Washington, " Anomalous metals", Condensed Matter Physics Seminar2:00pm
9/10
Prof. B. Spivak, Department of Physics, University of Washington, " Anomalous metals", Condensed Matter Physics Seminar
Tuesday, September 10th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Prof. B. Spivak, Department of Physics, University of Washington
Anomalous metals
The observation of metallic ground states in a variety of two-dimensional electronic systems poses a fundamental challenge for the theory of electron fluids. I will analyze evidence for the existence of a regime, which we call the "anomalous metal regime," in diverse 2D superconducting systems driven through a quantum superconductor to metal transition by tuning physical parameters such as the magnetic field, the gate voltage in the case of systems with a MOSFET geometry, or the degree of disorder. The principal phenomenological observation is that in the anomalous metal, as a function of decreasing temperature, the resistivity first drops as if the system were approaching a superconducting ground state, but then saturates at low temperatures to a value that can be orders of magnitude smaller than the Drude value. The anomalous metal also shows a giant positive magneto-resistance. This behavior is observed in a broad range of parameters. I will exhibit, by theoretical solution of a model of superconducting grains embedded in a metallic matrix, that as a matter of principle such anomalous metallic behavior can occur in the neighborhood of a quantum superconductor-metal transition. However, I will also argue that the robustness and ubiquitous nature of the observed phenomena are difficult to reconcile with any existing theoretical treatment and speculate about the character of a more fundamental theoretical framework. Prof. N. Berrah, Department of Physics, University of Connecticut, "Towards Making Molecular Movies", Graduate Student Seminar12:15pm
9/6
Prof. N. Berrah, Department of Physics, University of Connecticut, "Towards Making Molecular Movies", Graduate Student Seminar
Friday, September 6th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. N. Berrah, Department of Physics, University of Connecticut
Towards Making Molecular Movies
In the past decade, improved laser technology from the Infrared to the X-ray regime has allowed scientists to advance the frontiers of time-resolved ultrafast science. Table-top ultrafast lasers as well as Free Electron Lasers (FELs) science have been identified as one of the highest priority for funding agencies.
We have pursued photo-induced molecular dynamics research with complementary table-top as
well as XUV and X-ray FELs with the ultimate goal of making molecular movies. These movies
follow the electronic and nuclear dynamics induced by the absorption of photons by molecules that occur because of the coupling between the electronic and nuclear motion in the molecules. This coupling first leads to attosecond electron excitation within the molecules, followed by nuclear motion in the femtosecond range, eventually resulting in the formation and breaking of chemical bonds on the picosecond timescale. Research highlights will be presented. Dr. Molly Gallagher, Department of Physics,University of Connecticut, "Mapping Extragalactic Dense Molecular Gas: Ties to Environment and Star Formation ", Astronomy Seminar2:00pm
9/4
Dr. Molly Gallagher, Department of Physics,University of Connecticut, "Mapping Extragalactic Dense Molecular Gas: Ties to Environment and Star Formation ", Astronomy Seminar
Wednesday, September 4th, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. Molly Gallagher, Department of Physics,University of Connecticut
Mapping Extragalactic Dense Molecular Gas: Ties to Environment and Star Formation
Gas density plays an important role in galactic evolution via its connection to star formation. Yet because dense gas is difficult to observe, we are only beginning to explore how interstellar gas density and its relationship to the star formation rate depend on galactic environment. We will explore how gas density, star formation rate, and galactic environment interact on scales ranging from Galactic scale down to the scale of individual molecular clouds. This work relies on new dense gas observations of nearby spiral galaxies from the Atacama Large Millimeter/submillimeter Array (ALMA). Prof. V. Kharchenko, Department of Physics, University of Connecticut, "Non-equilibrium Processes in Atomic Science, Astrophysics, and Biology", Graduate Student Seminar12:15pm
8/30
Prof. V. Kharchenko, Department of Physics, University of Connecticut, "Non-equilibrium Processes in Atomic Science, Astrophysics, and Biology", Graduate Student Seminar
Friday, August 30th, 2019
12:15 PM - 01:15 PM
Storrs Campus GS-119
Prof. V. Kharchenko, Department of Physics, University of Connecticut
Non-equilibrium Processes in Atomic Science, Astrophysics, and Biology
Non-equilibrium processes arise in transitions between different steady /equilibrium states. Experimental and theoretical investigations of these processes are most formidable tasks for researches in various scientific disciplines, including quantum mechanics, plasma physics, astrophysics, climate change, and biology. Examples of theoretical analysis of non-equilibrium processes in atomic physics, astrophysics, and biology will be discussed and current research projects will be described.
Dr. Jan M Rost, Max Planck Institute for the Physics of Complex Systems, Dresden, Germany, Atomic, Molecular, and Optical Physics Seminar2:00pm
8/21
Dr. Jan M Rost, Max Planck Institute for the Physics of Complex Systems, Dresden, Germany, Atomic, Molecular, and Optical Physics Seminar
Wednesday, August 21st, 2019
02:00 PM - 03:00 PM
Storrs Campus GS-119
Dr. Jan M Rost,
Max Planck Institute for the Physics of Complex Systems,
Dresden, Germany
Sculpting electron dynamics through its environment
Interfacing an electron with a well-controlled environment can generate unusual dynamics, in particular if the electron is easily polarizable. The Rydberg Composite, a highly excited Rydberg electron whose spatial density encompasses many atoms or molecules on sites of a designed spatial lattice is one example. We will show that a 2D Composite with a two-dimensional lattice in form of an atomic monolayer has a particularly reach electron spectrum which features energy bands and exhibits regular as well as chaotic features depending on the ratio of lattice spacing and the wavelength of the Rydberg wave function. Possibilities for experimental realizations in the ultracold will be discussed.
The second part of the talk concerns noisy photo electron spectra as generated, e.g., by short and intense SASE free electron laser pulses. Learning the corresponding electron dynamics with a deep neural network by introducing synthetic Hamilton matrices, we can purify the spectrum as if it would have been created with a normal Gaussian pulse. Perspectives of this novel way to construct ultrafast electron dynamics from given noisy spectra will be discussed. Prof. Keith Horne, University of St. Andrews, "Echo Tomography of Black Hole Accretion Flows in Active Galactic Nuclei", Special Astronomy Seminar2:00pm
7/26
Prof. Keith Horne, University of St. Andrews, "Echo Tomography of Black Hole Accretion Flows in Active Galactic Nuclei", Special Astronomy Seminar
Friday, July 26th, 2019
02:00 PM - 03:00 PM
Storrs Campus Gant West P121
Prof. Keith Horne,
University of St. Andrews
Echo Tomography of Black Hole Accretion Flows in Active Galactic Nuclei
Echo Tomography uses light travel time delays to resolve micro-arcsecond structure of black hole accretion flows in active galactic nuclei. I will discuss methods used to map the temperature-radius profile of black hole accretion discs, and to construct velocity-delay maps that probe the geometry, kinematics and ionisation structure of the associated broad emission-line regions. In particular, I will present results from the 2014 STORM campaign using HST, Swift, and ground-based telescopes to monitor spectral variations in the Seyfert galaxy NGC 5548. I will discuss anomalous behaviour observed during the campaign, and present a determination of the inclination and temperature-radius profile of its accretion disc and velocity-delay maps exhibiting evidence for an inclined Keplerian flow extending from 2 to 20 light days. Tilting the inner disc to align with black hole spin may help to address several features we are seeing in the reverberation mapping studies. Dissertation Defense, Niraj Ghimire- Density Matrix Renormalization Group studies of interacting dipoles in a zigzag chain- Ph. D. defense11:00am
6/26
Dissertation Defense, Niraj Ghimire- Density Matrix Renormalization Group studies of interacting dipoles in a zigzag chain- Ph. D. defense
Wednesday, June 26th, 2019
11:00 AM - 01:00 PM
Storrs Campus Gant West Room 103-A
Dissertation Defense
Niraj Ghimire
Physics Department
University of Connecticut
"Density Matrix Renormalization Group studies of interacting dipoles in a zigzag chain"
The goal of my research is to simulate quantum mechanics, which is known to be a very challenging problem even for the most advanced supercomputers of today. The system I have chosen consists of molecular dipoles in a quasi-one-dimensional optical lattice. For the first part of the talk, I will discuss the situation where the dipoles are polarized in the plane of the lattice at half-filling and double occupancy is not allowed on any lattice sites. The dipoles can hop around between sites and the interactions between them can be attractive or repulsive, with the hopping and interaction allowed up to second neighbors. I am particularly interested in the zero-temperature quantum phases induced by geometrical frustration, a situation where not all the interactions are satisfied. By mapping the dipoles in this lattice to a spin-1/2 model and by using the numerical approximation method known as density matrix renormalization group (DMRG), I have studied this system and produced a complex phase diagram.
For the second part of the talk, I will discuss the situation where a dipole is trapped in each lattice site such that the dipole moment vector can be oriented in any direction. The dipoles interact with one another via dipole-dipole potential and also interact with the external field, but they do not hop around between lattice sites. I will talk about some results for this classical model. Then I will explain how I have mapped it to a spin-2 model (which is quantum mechanical) and explain some results obtained using DMRG.
Major Advisor: Dr. Susanne Yelin
Wednesday, June 26, 2019
11:00 AM
Gant Science Complex
GW-103A