Professor Donna Strickland , Katzenstein Distinguished Lecturer, March 13, 2020
The University of Connecticut, Department of Physics, is proud to announce that on March 13, 2020, Professor Donna Strickland of the Department of Physics and Astronomy at the University of Waterloo will be presenting the 2020 Distinguished Katzenstein Lecture. Prof. Strickland is one of the recipients of the 2018 Nobel Prize in Physics for developing […]
[Read More]2019-Newsletter Department Head Greeting
Insight from APS: Careers in Physics
What is a Bachelors of Science degree in Physics good for? What kinds of jobs are available to graduates who complete a 4-year degree in physics, but decide not to pursue an advanced degree? How does a physics degree stack up against other STEM fields in terms of employment options in today’s highly competitive job […]
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Ron Mallett Featured on NBC Connecticut
Could traveling into the past be part of our future? Quite possibly, says Ron Mallett, a UConn emeritus professor of physics who has studied the concept of time travel for decades. Earlier this month, he spoke with NBC Connecticut reporter Kevin Nathan about his life and work as a theoretical physicist, and discussed how time […]
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UConn Today: A New Phase for the Gant Science Complex
The UConn Today published an article highlighting the state of 10-year renovation of the Gant Science Complex. The Complex was first constructed between 1974 and 1978 and was home to the departments of mathematics and physics for several decades. The renovation to this 285,00 square-foot campus landmark is part of Next Generation Connecticut, the initiative […]
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Professor Jocelyn Bell Burnell – 2019 Katzenstein Lecturer
The UConn Physics Department is delighted to announce that our 2019 Distinguished Katzenstein Lecturer will be Professor Dame Jocelyn Bell Burnell. Professor Dame Jocelyn Bell Burnell is world-famous for her discovery of pulsars in 1967. Pulsars are a special type of neutron star, the rotating dense remnant of a massive star. Pulsars have highly magnetic surfaces, and emit a beam of electromagnetic radiation […]
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Research Spotlight: Exploring the nature of the universe with Dr. Thomas Blum
The Daily Campus published an article highlighting the research of Prof. Thomas Blum about Quantum Chromodynamics, a theory which describes the interactions between elementary particles. The development of this theory could help further understanding of the Standard Model of particle physics. The Standard Model is what physicists use to describe the fundamental building blocks of […]
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Astronomer Jonathan Trump interviewed on UConn 360
UConn Astrophysicist and observational astronomer Jonathan Trump was a recent guest on UConn 360, a podcast from the Storrs campus of the University of Connecticut. In this conversation, Jonathan tells about how attending a lecture as an undergraduate at Penn State captured his interest and changed the course of his professional career. Now Jonathan offers […]
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Greetings from the Department Head
New building, new teaching approach, new people – there is a lot of change and excitement in the air for the Physics Department in 2019. The most obvious change is that physics has moved into a newly renovated building. What most alumni will remember as the Math Building has been taken down to its frame […]
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Breaking Up is Hard To Do (for Electrons in High Temperature Superconductors)
Physicists used to think that superconductivity – electricity flowing without resistance or loss – was an all or nothing phenomenon. But new evidence suggests that it’s not so clear cut, at least in copper oxide superconductors. “If we understood why copper oxide is a superconductor at such high temperatures, we might be able to synthesize a better one”, says UConn physicist Ilya Sochnikov. Sochnikov and his colleagues at Rice University, Brookhaven National Lab and Yale recently figured out part of that puzzle, and they report their results in the latest issue of Nature.
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Daniel McCarron wins NSF Early Career Award
Daniel McCarron, assistant professor of physics, the College of Liberal Arts and Sciences, will receive $645,000 over five years for his work on the development of techniques to trap large groups of molecules and cool them to temperatures near absolute zero. The possible control of molecules at this low temperature provides access to new research applications, such as quantum computers that can leverage the laws of quantum mechanics to outperform classical computers.
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Meet the Researcher: Carlos Trallero
When Carlos Trallero started his academic career in physics, he had no idea he would become a pioneer in a field of research that uses high-power lasers to investigate atomic and molecular physical phenomena. Originally from Cuba, where there isn’t much funding for experimental research, Trallero began his academic career by studying theoretical physics. But as a senior graduate student at Stony Brook University, he got the chance to work in a lab doing experimental work and quickly recognized it was his true passion.
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International Summer School “Strong interactions beyond simple factorization”
May 27-June 5 UConn Physics Department hosted an international summer school Strong interactions beyond simple factorization: collectivity at high energy from initial to final state. The school was supported by an NSF grant to Prof. Kovner and was devoted to modern approaches to the physics of high energy hadronic and heavy ion collisions.
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Amelia Henkel, Graduating President of the Undergraduate Women in Physics Club, speaks about her time at UConn
Amelia Henkel, graduating Double Major in Physics and Human Rights, and President of the Undergraduate Women in Physics Club, speaks on the CLAS website about her passion for physics and human rights, and how she mastered challenges in her remarkably interdisciplinary curriculum. “We really need to interact with other disciplines,” says Amelia, “because that’s […]
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2019 Pollack Lecture
On April 11th and 12 of 2019 Prof. Paul Corkum of the Joint Attosecond Laboratory (University of Ottawa and the National Research Council of Canada) visited the department. Prof. Corkum’s main area of research is on the interaction of ultrashort laser pulses with matter broadly defined. His most notable contribution is perhaps the discovery of […]
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Astronomers Assemble View of Evolving Universe
The University of Connecticut’s Katherine Whitaker is part of a team of astronomers who have put together the largest and most comprehensive “history book” of the universe from 16 years’ worth of observations from NASA’s Hubble Space Telescope.This image, a mosaic of nearly 7,500 separate Hubble exposures, presents a wide portrait of the distant universe and contains roughly 265,000 galaxies that stretch back through 13.3 billion years to just 500 million years after the Big Bang.
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UConn Physics Professor elected to AAAS
UConn physics professor Nora Berrah has been elected to the historic and prestigious American Academy of Arts and Sciences. This year, more than 200 individuals were elected to the academy with compelling achievements in academia, business, government, and public affairs. Berrah, who was head of the physics department from 2014 to 2018, has been recognized […]
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UConn Astronomers React to First Photo of a Black Hole
This image is the first ever taken of a black hole, captured by the Event Horizon Telescope (EHT) project. The black center is a direct view of the event horizon of a supermassive black hole with a mass of 6.5 billion times the Sun, lying at the center of the Virgo cluster of galaxies. The bright ring is emission from hot gas just above the event horizon, with an asymmetric shape caused by gravitational lensing of light in the strong gravity of the black hole. The EHT collaboration captured the image using a network of 8 radio telescopes that spanned the Earth.
[Read More]Charles Reynolds Lecture 2018: Prof Andrew Millis
The 2018 Reynolds lecture speaker was Prof Andrew Millis, a Professor of Physics at Columbia University and a co-Director of Center for Computational Quantum Physics at the Flatiron Institute. Dr. Millis’s research focus is theoretical condensed matter physics. He is the leading authority in theory of correlated materials, application of new theoretical ideas to actual […]
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2 for the price of 1: UConn researcher finds new mechanism making double ionization an efficient process
An international research team headed by Dr. Aaron LaForge from the research group of Prof. Nora Berrah in the Physics department at UConn has recently discovered a new type of decay mechanism leading to highly efficient double ionization in weakly-bound systems. The team has published its results in the science journal “Nature Physics”. Ionization is […]
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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.