Prof.. Reina Maruyama,Yale University

What is dark matter?

Astrophysical observations give overwhelming evidence for the existence of dark matter. Several theoretical particles have been proposed as dark matter candidates, including weakly interacting massive particles (WIMPs), axions, and, more recently, their much lighter counterparts. However, there has yet to be a definitive detection of dark matter. For years, one group, the DAMA collaboration, has asserted that they observe a dark matter-induced annual modulation signal in their NaI(Tl)-based detectors. Their observations are inconsistent with those from other direct detection dark matter experiments under most assumptions of dark matter. In this talk, I will describe how I came to work on this topic and the debate’s current status, the worldwide experimental effort to test this extraordinary claim, and our progress toward resolving the current stalemate in the field.

Note: The pre-colloquium reception will be 3-4pm in the Gant Light Court

Graduate student Mitchell Bredice, Department of Physics, University of Connecticut

Kinetics, Nucleation, and Relaxation Dynamics of Ion-Seeded Nanoparticles

The recent interest in studying the adsorption and emission spectra of the hazy atmospheres of exoplanets stimulates the interest in clusters, small aggregates of atoms or molecules. The nucleation and dynamics of nanoparticles in the Earth’s atmosphere and their impact on the global climate and environment is another important area of research stimulating investigations of nucleation processes. However, how these small aggregates form is not wholly understood. Traditionally, nucleation of clusters or other phases is described through Classical Nucleation Theory. Although this theory has many discrepancies in describing the nucleation of submicron particles. In this work, we have performed molecular dynamics simulations of the nucleation of ion-seeded nanoparticles, specifically ArnH+ clusters, to investigate the microscopic mechanisms of nucleation from a gas or liquid phase. From these simulations, we have studied the stages of the nonequilibrium and equilibrium growth of ArnH+ clusters and analyzed the size distribution and internal energy relaxation of nascent clusters during different stages of their growth. The fundamental impact of the internal energy relaxation on the nonequilibrium nucleation of small ArnH+ clusters has been demonstrated. This analysis has generally been avoided in previous investigations due to assumptions of the equilibrium nature of the nucleation process. The results of our simulations showed that nanoparticles are formed in highly excited states, thus the cluster growth and relaxation are concurrent processes, and that relaxation of the cluster internal energy can delay cluster growth processes. To further investigate the internal energy relaxation, an ensemble of molecular dynamics simulations was performed for the detailed analysis of the average time evolution of kinetic, potential, and total energies of small ArnH+ clusters, and their kinetic energy relaxation. The results of the performed simulations have been explained through the use of a collisional Boltzmann equation describing the energy relaxation processes. Lastly, the general relationship between nonequilibrium growth and internal energy relaxation is discussed.

Prof. Cassandra Paul (San Jose State University)

Title and abstract (TBD)

Contact: Prof. Erin Scanlon

Remote talk (details forthcoming)

Dr. Esteban Goetz, Department of Physics, University of Connecticut

Interferometric Harmonic Spectroscopy for Electron Dynamics Imaging and Attosecond Pulse Train Phase Characterization

The advent of ultrashort light pulses has opened the possibility of investigating atomic and molecular processes on their natural time scales. In particular, Attosecond Transient Absorption Spectroscopy (ATAS) [1], a technique that allows to time-resolve the quantum dynamics of electrons by monitoring the absorption of extreme ultraviolet (XUV) radiation by an atomic or molecular system when the latter is dressed by an infrared (IR) laser source.

Motivated by recent experimental advances in self-referenced interferometric harmonic spectroscopy [2], we theoretically investigate an alternative approach to ATAS for electron dynamics imaging and attosecond pulse train (APT) phase characterization. In contrast to ATAS, which gives access to the imaginary part of the refractive index through an absorption measurement, an interferometric phase measurement gives information of its real part. In this talk, I will discuss the link between the XUV phase measurements of Ref. [2] and the different photoexcitation pathways occurring at the atomic level which are imprinted in the real part of the macroscopic refractive index. As an application, we show how such an interferometric approach can be used for phase retrieval of attosecond pulse trains based on two-arm harmonic spectroscopy and an optimization algorithm. Finally, I will highlight the impact of spin-orbit couplings and macroscopic and field propagation effects on the phase measurements and APT phase retrieval. Our theoretical description is based on numerical solution of the scalar Maxwell equations beyond Beer’s Law for the macroscopic field propagation coupled to the time-dependent Schroedinger equation for the quantum dynamics.

[1] M. Holler et al., Phys. Rev. Lett. 106, 123601 (2011)

[2] G. R. Harrison et al., arXiv:2305.17263 (2023)

Prof. Claudio Chamon, Boston University

Circuit complexity and functionality: a thermodynamic perspective

We explore a link between complexity and physics for circuits of given functionality. Taking advantage of the connection between circuit counting problems and the derivation of ensembles in statistical mechanics, we tie the entropy of circuits of a given functionality and fixed number of gates to circuit complexity. We use thermodynamic relations to connect the quantity analogous to the equilibrium temperature to the exponent describing the exponential growth of the number of distinct functionalities as a function of complexity. This connection is intimately related to the finite compressibility of typical circuits. Finally, we use the thermodynamic approach to formulate a framework for the obfuscation of programs of arbitrary length – an important problem in cryptography – as thermalization through recursive mixing of neighboring sections of a circuit, which can viewed as the mixing of two containers with “gases of gates”. This recursive process equilibrates the average complexity and leads to the saturation of the circuit entropy, while preserving functionality of the overall circuit. The thermodynamic arguments hinge on ergodicity in the space of circuits which we conjecture is limited to disconnected ergodic sectors due to fragmentation. The notion of fragmentation has important implications for the problem of circuit obfuscation as it implies that there are circuits with same size and functionality that cannot be connected via local moves. Furthermore, we argue that fragmentation is unavoidable unless the complexity classes NP and coNP coincide.

Community event for viewing the April 8 solar eclipse, hosted by UConn faculty and students.

90% of the Sun will be eclipsed from our location at maximum 3:25pm

Activities include:

• solar telescopes
• pinhole camera installation, and camera-making demos
• eclipse demos
• eclipse-viewing glasses for sale(fundraisers for undergrad + graduate physics organizations) 

TITLE:

Quantum acoustics and the physics of the strange metals

ABSTRACT:

Quantum acoustics is the analog of quantum optics, with phonons playing the role of photons. The classical fields (electromagnetic, acoustic) are reached by virtue of coherent states in both cases. Quantum acoustics leads to two time dependent, interacting wave fields, one lattice, one quantum. The electron diffuses at a Planckian rate, independent of electron-lattice coupling and temperature, and the calculated resistivity is linear in temperature. Mott-Ioffe-Regel and Drude peak mysteries are also resolved. A rather different carrier transport scenario emerges for the strange metals.

Dr. Paul M. Eugenio, University of Connecticut

Tunable moire sublattices in twisted square homobilayers: exploiting fundamental principles for new technologies

Stacking and twisting atomically thin bilayers at small angles produces an approximate periodic pattern, due to the overlap of the crystal layers. These devices, dubbed “moire” bilayers, exhibit a high degree of tunability and variability: through choice of twist angle, constituent layers, and gating. To date, a number of such devices have been built which have demonstrated a plethora of novel phases, including non-trivial topology and Mott physics. Despite this explosion in moire research, moire bilayers have been almost exclusively formed from layers with triangular/hexagonal crystal geometry, and where the valence bands are centered on the Gamma or K/K’ high symmetry points. Here we theoretically demonstrate that moire devices formed from square bilayers can be used to simulate the ground state of the Hubbard model, but where the ratio of the nearest-neighbor (t) and next-to-nearest neighbor (t’) tunneling can be tuned between zero and infinity, in situ via an electric field. If experimentally realized, such a device would be the first of its kind, and would open a pathway toward the testing of a number of proposed exotic phases, such as a spin-liquid and d+id superconductivity. Most importantly, the square Hubbard model is a quintessential model for high-Tc in cuprates, where numerics has demonstrated the absence of superconductivity when t’=0.

Graduate student Geoff Harrison, Department of Physics, University of Connecticut

ITAS: A Technique for Complete Quantum Measurements on a New Timescale

Transient absorption spectroscopy is a well-established technique used to study electron dynamics in atomic and molecular systems but typically can only measure the magnitude of the electronic wavefunction. We have integrated interferometric methods into this technique to allow complete quantum measurements of both the magnitude and phase of electronic wavefunctions. A spatial light modulator (SLM) is used to separate the interferometric arms in an extremely stable way, enabling the measurement of effects on the zeptosecond timescale (with a jitter of 3zs). In this talk, I’ll describe how we’ve utilized SLMs to make these measurements possible and share some initial data we’ve taken looking at phase effects in argon.

Dr. Fatma Aslan, Jefferson National Laboratory and UConn

Hadron structure-oriented approach to TMD phenomenology

We present a first practical implementation of a recently proposed hadron structure oriented (HSO) approach to TMD phenomenology applied to Drell-Yan like processes. We compare and contrast general features of our methodology with other common practices and emphasize the improvements derived from our approach that we view as essential for applications where extracting details of nonperturbative transverse hadron structure is a major goal. These include the HSO’s preservation of a basic TMD parton-model-like framework even while accounting for full TMD factorization and evolution, explicit preservation of the integral relationship between TMD and collinear PDFs, and the ability to meaningfully compare different theoretical models of nonperturbative TMD parton distributions.

Dr. Nick Hutzler, California Institute of Technology

UConn Physics Colloquium

Title and abstract: TBD

Contact: Profs. Tom Blum and Dan McCarron

Dr. J. I. A. Li, Brown University

The Superconducting Diode Effect And Spontaneous Symmetry Breaking In Multi-Layer Graphene

The superconducting diode effect, defined as nonreciprocity in the critical supercurrent, provides a unique window into the nature of the superconducting phase. It has been argued that a zero-field diode effect in the superconducting transport requires inversion and time-reversal symmetries to be simultaneously broken. Along this vein, the zero-field superconducting diode effect in multi-layer graphene provides direct evidence of the microscopic coexistence between superconductivity and time-reversal symmetry breaking. In this talk, I will discuss our recent efforts that utilize the angle-resolved measurement of transport nonreciprocity to directly probe the nature of spontaneous symmetry breaking in the normal phase. By investigating the interplay between transport nonreciprocity, ferromagnetism, and superconductivity, our findings suggest that the exchange-driven instability in the momentum space plays a key role in the zero-field superconducting diode effect.

Title: A comprehensive insight into nucleons at the Electron-Ion Collider

Abstract:
Quantum Chromodynamics (QCD) is the theory governing the strong interactions that bind quarks and gluons, collectively known as partons, to form nucleons - the fundamental building blocks of visible matter. Achieving a profound understanding of the partonic structure of nucleons stands as a crucial milestone, and the forthcoming Electron-Ion Collider (EIC) at the Brookhaven National Laboratory is poised to be the ultimate tool in nuclear physics for this purpose. In this talk, I will explore a few of my research endeavors, aiming to address key questions such as, “How can we measure the orbital motion of partons within nucleons?” and “How can we uncover quantum anomalies in the distributions of partons within nucleons, and what can we learn from them?” The state-of-the-art theory discussed in this talk plays a pivotal role in providing comprehensive insight into nucleons, exploring the origins of spin, mass, and symmetry breakings - all of which form the bedrock of QCD and the EIC.

Graduate student Debadarshini Mishra, Department of Physics, University of Connecticut

Imaging ultrafast dynamics in molecular systems

Imaging electronic and molecular dynamics at the attosecond and femtosecond timescales is crucial for understanding the mechanisms of chemical reactions, a fundamental aspect in fields ranging from materials science to biochemistry. This in-depth understanding of chemical processes may allow for precise control over reaction dynamics, thereby paving the way for advancements in technology and medicine, for example, by guiding the development of efficient catalysis, innovative materials, and targeted drugs. In this talk, I will describe our work on imaging time-resolved molecular dynamics using two distinct and complementary techniques.

In the first part of my talk, I will discuss the use of coincident Coulomb explosion imaging for the direct visualization of roaming reactions. These reactions represent unconventional pathways that allow fragments to remain weakly bonded, leading to the formation of unexpected final products. Typically, the neutral character of the roaming fragment and its indeterminate trajectory make direct experimental identification challenging. However, I will demonstrate that by leveraging the power of coincidence imaging, we can reconstruct the momentum vector of the neutral roamer and thus identify an unambiguous signature for roaming.

In the second part of my talk, I will discuss the imaging of UV-induced ring-opening and dissociation dynamics using ultrafast electron diffraction. I will demonstrate that by harnessing the superior temporal and structural resolution of this technique, we can explore the competition among different molecular pathways as well as their wavelength-dependent behavior.

Dr. Andrey Tarasov, North Carolina State University

Title: Hadron as a many-body parton system: from parton interactions to non-perturbative phenomena

Due to the phenomenon of confinement, the hadron cannot be understood as a compound state of independent quarks and gluons but rather represents a strongly bounded many-body parton system. The dynamics of this system gives rise to such fundamental properties of the hadron as spin and mass. How the spin and mass of the hadron arise from the parton dynamics is an outstanding question of modern nuclear science. The parton dynamics can be probed in high-energy scattering experiments using the factorization approach. However, there is a wide class of observables that cannot be described within the conventional factorization schemes due to various reasons, including non-perturbative phenomena. In my talk, I will give several concrete examples and propose a solution based on applying the background field techniques, which provide a unified treatment of parton interactions. I will argue that the application of such techniques allows us to obtain a complete picture of the multi-parton dynamics in QCD and shed light on the origin of the proton spin and mass.

Dr. James Cryan, SLAC National Lab (UConn Physics Colloquium)

Ultrafast dynamics using X-ray attosecond pulses.

Contact: Prof. Nora Berrah

Prof. Moshe Gai and Grad. Student Deran Schweitzer, Department of Physics, University of Connecticut

Stellar Evolution: Supernovae

Dr. Adam Freese, Jefferson Lab

Title: Relativistic mass densities: from the light front to generalized parton distributions

Abstract: The dynamical generation of mass is one of the most fascinating aspects of quantum chromodynamics. Partonic imaging allows us to probe where this generated mass is, and to break it down into contributions from quarks and gluons. In particular, imaging gives us access to generalized parton distributions, which provide a relativistic three-dimensional picture of the proton’s internal structure, in terms of two spatial dimensions and a momentum faction x. In this talk, I examine how the light front provides a means of rigorously describing spatial distributions for relativistic systems (such as the proton), how the energy-momentum tensor provides distributions of energy and momentum, and how x-weighted moments of generalized parton distributions give us the most promising empirical means of accessing the mass distribution in the proton. I will review challenges in empirically accessing the GPDs, as well as ongoing efforts to address these challenges.

Prof. Jed Pixley, Rutgers University

Novel Strongly Correlated Phases in Stacked TMD Bilayers

Two-dimensional transition metal dichalcogenides (TMDs) have emerged as an exciting platform to stack and twist bilayers to engineer strongly correlated quantum phases. Here we present a theory to describe the recent realization of a heavy fermion state in stacked MoTe2/WSe2 bilayers. An extension of this theory that allows for the formation of unconventional superconductivity through repulsive nearest neighbor interactions will be used to show how to realize the p-wave BEC to BCS transition.

Dr. Wenliang Li, Stony Brook University

Title: Probing Proton’s Identity using the Electron-Ion Collider

Abstract:

The Electron-Ion Collider, being constructed at the Brookhaven National Lab, is the “dream machine” for nuclear physics studies for the upcoming decades. The diverse capability in the accelerator design offers physicists a unique opportunity to study quark and gluon structures within nucleons and nuclei. Furthermore, the production and detection of the rare isotopes is a possibility.

In this seminar, we will dive into two examples of many creative ways to use the EIC. 1. Probing the proton’s identity (baryon number), and determining who carries the baryon number within its wavefunction: gluon? quark? Both? 2. EIC can collide the electron beam on an ion beam with any atomic mass, could we use it to create and study the rare isotope (via eA collision) to complement the low-energy studies at FRIB?

Dr. Jaspreet Singh Randhawa, Los Alamos National Laboratory

Title: Nuclear reaction studies to decode the observations from neutron stars in binary systems

Abstract: Neutron stars are ideal astrophysical laboratories to test theories of dense matter physics as they may exhibit most exotic forms of matter, and are pivotal in driving nucleosynthesis in various explosive astrophysical environments; e.g X-ray binaries, neutron star mergers. Breath-taking multi-messenger observations of explosive astronomical events are generating exciting new challenges for nuclear physics and force a rethinking of old paradigms. For X-ray binaries, surface nuclear burning proceeds through extremely proton-rich nuclei powering the X-ray bursts, whereas in neutron star mergers nucleosynthesis proceeds through very neutron-rich nuclei. Therefore, to understand the energy generation and nucleosynthesis in these extreme environments, new nuclear data on very exotic nuclei is required, e.g. nuclear reaction rates or detailed nuclear structure/properties of exotic nuclei. Facility for Rare Isotope Beams (FRIB), a newly developed world’s leading radioactive ion beam facility, will provide an unprecedented access to the very exotic proton-rich and neutron-rich nuclei. In this talk, I will highlight the need for new nuclear physics data to decode observations from X-ray binaries and neutron star mergers, and how FRIB is opening up a new window to explore the most exotic nuclei on earth, to provide much-needed data to facilitate model-observation comparison of various astrophysical environments. I will present the new results from on-going reaction studies at FRIB, and will discuss planned measurements, which will help us to answer some of the most important questions in nuclear astrophysics.

Dr. Riccardo Longo, University of Illinois Urbana-Champaign

Title: Probing Hot & Cold QCD Phenomena Using Jets

Abstract:

The LHC Heavy Ion program offers unique opportunities to study Quantum Chromodynamics (QCD) phenomena at various length and temperature scales. In particular, dijets are fantastic probes for exploring emergent QCD properties in different regimes. Hadronic Pb+Pb collisions create a hot and dense medium composed of quarks and gluons, the Quark Gluon Plasma (QGP). Dijets produced by a hard-scattering can be used to investigate the microscopic properties of this nearly perfect fluid. Conversely, measuring dijets in p+Pb collisions allows for studying different proton size configurations and cold nuclear effects that modify the nucleon Parton Distribution Functions (PDFs) when bound into atomic nuclei. Studies to inform nuclear PDF (nPDF) parametrization can also be carried out by analyzing dijets produced in photo-nuclear events, allowing for investigating a unique kinematic regime. Other aspects of the nucleon structure, such as its spin composition, are studied at CERN fixed target experiments by performing polarized DIS and Drell-Yan measurements. In my talk, I will discuss selected aspects of hot and cold QCD addressed by the ATLAS Heavy Ion and COMPASS experiment programs. In particular, I will present recent dijet measurements in p+Pb and Pb+Pb collisions at ATLAS and recent COMPASS polarized Semi-Inclusive DIS and Drell-Yan results.

Finally, I will show how the cold QCD effort will naturally continue in the research avenues that the Electron-Ion Collider will open.

Dr. François Légaré, Institut national de la recherche scientifique, Energy Materials Télécommunications center

Ultrafast IR/mid-IR laser technologies and their applications at ALLS

The Advanced Laser Light Source (ALLS) is a unique user facility located at INRS-EMT (Varennes, Canada) counting on 40M CDN$ of investment since 2002. Since 2019, this facility has jointed the LaserNetUS network and is now funded as a national research infrastructure by the Canada Foundation for Innovation – Major Science Initiatives. These fundings ease access to the facility for academic and government users. In the first part of my talk, I will give an overview of the facility’s capabilities including the most powerful laser in Canada with 750 TW. In the second part, I will discuss novel approaches developed by my team for the generation of ultrashort pulses in the IR and mid-IR spectral range. This includes multidimensional solitary states in hollow core fibers [1,2] as well as using the frequency domain optical parametric amplification for the generation of tunable CEP stable mid-IR laser pulses [3,4]. Pulse characterization in the mid-IR spectral range will be presented [5]. Finally, I will present recent results on the generation of high-dose MeV electrons from tight focussing in air [6].

References

[1] R. Safaei, G. Fan, O. Kwon, K. Légaré, P. Lassonde, B. E. Schmidt, H. Ibrahim, and F. Légaré (2020), High-energy multidimensional solitary states in hollow core fiber, Nature Phot. 14, 733-739.

[2] L. Arias, A. Longa, G. Jargot, A. Pomerleau, P. Lassonde, G. Fan, R. Safaei, P. Corkum, F. Boschini, H. Ibrahim, and F. Légaré, Few-cycle Yb laser source at 20 kHz using multidimensional solitary states in hollow-core fibers, Opt. Lett. 47, 3612-3615 (2022).

[3] A. Leblanc, G. Dalla-Barba, P. Lassonde, A. Laramée, B. Schmidt, E. Cormier, H. Ibrahim, and F. Légaré (2020), High-field mid-infrared pulses derived from frequency domain optical parametric amplification, Opt. Lett. 45, 2267-2270.

[4] G. Dalla-Barba, G. Jargot, P. Lassonde, S. Tóth, E. Haddad, F. Boschini, J. Delagnes, A. Leblanc, H. Ibrahim, E. Cormier, and F. Légaré, Mid-infrared frequency domain optical parametric amplifier, Opt. Express 31, 14954-14964 (2023).

[5] A. Leblanc, P. Lassonde, S. Petit, J.-C. Delagnes, E. Haddad, G. Ernotte, M. R. Bionta, V. Gruson, B. E. Schmidt, H. Ibrahim, E. Cormier, and F. Légaré (2019), Phase-matching-free pulse retrieval based on transient absorption in solids, Opt. Express 27, 28998.

[6] S. Vallières, J. Powell, T. Connell, M. Evans, M. Lytova, F. Fillion-Gourdeau, S. Fourmaux, S. Payeur, P. Lassonde, S. MacLean, and F. Légaré, High Dose-Rate MeV Electron Beam from a Tightly-Focused Femtosecond IR Laser in Ambient Air (2024), Laser Photonics Rev. 18, 2300078.

François Légaré is a chemical physicist who specializes in developing novel approaches for ultrafast science and technologies, as well as biomedical imaging with nonlinear optics (Ph.D. in chemistry, 2004 – co-supervised by Profs. André D. Bandrauk and Paul B. Corkum). Full professor (2013 - …) at the Energy Materials Telecommunications center of the Institut national de la recherche scientifique (INRS-EMT), he was the director of the Advanced Laser Light Source (ALLS) until 2023. Since 2022, he is the director of the INRS-EMT center and CEO of ALLS. Under his scientific leadership, INRS has received in 2017 a grant of 13.9M CDN$ from the Canada Foundation for Innovation and the Quebec government, with 11.9M CDN$ to upscale the ALLS facility with high average power Ytterbium laser systems and advanced instrumentation for time-resolved material characterization. He is a Fellow and senior member of OPTICA and Fellow of the American Physical Society. He is a member of The College of New Scholars, Artists and Scientists of the Royal Society of Canada (2017). He was awarded the Herzberg medal from the Canadian Association of Physics in 2015 and the Rutherford Memorial Medal in physics of the Royal Society of Canada in 2016. He has contributed to about 200 articles in peer reviewed journals including prestigious ones such as Nature, Science, Nature Photonics, Nature Physics, Nature Communications, and Physical Review Letters. According to Google Scholar, his h-index is 59 with more than 13,000 citations.

UConn Physics Colloquium: Dr. Andrew Held

High Power Commercial Laser Markets and Applications

Abstract: Ubiquitous and familiar applications for lasers include telecom data transmission, laser surgery (LASIK), information processing (DVD/Blue Ray), supermarket scanners, laser pointers and a multitude of laser sensing applications (LIDAR, range finders, facial recognition, etc.). Sophisticated laser technology is also well-recognized as a key, enabling research tool.

Perhaps less well known are the “unsung” commercial applications and markets for higher power lasers. Often out of public view, these laser applications drive diverse and massive commercial markets and are supported by extensive industry-based research and development investments. And are generating increasingly abundant STEM based career opportunities.

The presentation will highlight the laser technologies and applications used in materials processing to mark, engrave, cut, and join everything from shoe leather to sheet metal. Also covered are laser applications supporting the manufacturing of microelectronics-based consumer technology, enabling higher performing devices and ever larger displays. The laser technology and developments that support emerging Directed Energy military applications will be also be reviewed.

Bio:

Andrew Held has recently retired as Senior Vice President of Coherent’ s Aerospace and Defense business. Andrew has over 30 years’ experience in General Business Management, Research, Sales and Marketing of lasers and photonics into a broad range of markets and applications. He received his B.S. in Chemistry and Ph.D. in Laser Spectroscopy from the University of Pittsburgh and was an Alexander von Humboldt Research Fellow at the Technical University in Munich.

Prof. Alexander Balatsky, Department of Physics, University of Connecticut

Dynamics and Quantum Sensing: magnetism, gravity and q-bit sensors

Dr. Thomas Weinacht, Stony Brook University

Long Lived Electronic Coherences in Molecules

I will discuss experiments and calculations that demonstrate long lived electronic coherences in molecules using a combination of measurements with shaped octave spanning ultrafast laser pulses, 3D velocity map imaging and calculations of the light matter interaction. Our pump-probe measurements prepare and interrogate entangled nuclear-electronic wave packets whose electronic phase remains well defined despite vibrational motion along many degrees of freedom. The experiments and calculations illustrate how coherences between excited electronic states survive even when coherence with the ground state is lost, and may have important implications for light harvesting, electronic transport and attosecond science.

Dr. Josiah Sinclair, MIT

A new platform for quantum science: programmable arrays of single atoms inside an optical cavity.

Recently, programmable arrays of single atoms have emerged as a leading platform for quantum computing and simulation with experiments demonstrating control over hundreds of atoms [1]. Interfacing an atom array with a high-quality optical cavity promises even greater control and new capabilities. By coupling atoms to an optical cavity, we can more efficiently collect light from each atom improving detection. In addition, an optical cavity can be used to efficiently entangle many atoms in a single step relying on a novel technique called counterfactual carving [2]. I will describe our progress towards the goal of detecting and correcting errors on a register of Rubidium atoms selectively coupled to a large-waist optical cavity. Beyond detecting errors, applying corrections requires real-time feedback, and I will present a simple experiment demonstrating that fast feedback on microsecond timescales can already improve measurement fidelity. Finally, I will describe our accidental realization that we can use our cavity to directly observe collisions between pairs of trapped atoms in real time.

Dr. Yossathorn Tawabutr, University of Jyväskylä

Fully Consistent NLO Calculation of Forward Single-Inclusive Hadron Production in Proton-Nucleus Collisions

We study the single-inclusive particle production from proton-nucleus collisions in the dilute-dense framework of the color glass condensate (CGC) at next-to-leading order (NLO) accuracy. In this regime, the cross section factorizes into hard impact factors and dipole-target scattering amplitude describing the eikonal interaction of the partons in the target color field. For the first time, we combine the NLO impact factors with the dipole amplitude evolved consistently using the NLO Balitsky-Kovchegov (BK) equation with the initial conditions fitted to HERA structure function data.

The resulting neutral pion cross section with all parton channels included are qualitatively consistent with the recent LHCb measurement. In particular, the NLO evolution coupled to the leading order impact factor is shown to produce a large Cronin peak that is not visible in the data, demonstrating the importance of consistently including NLO corrections to all the ingredients. Furthermore, the transverse momentum spectrum is found to be sensitive to the resummation scheme and the running coupling prescription in the BK evolution. This demonstrates how additional constraints for the initial condition of the BK evolution can be obtained from global analyses including both the HERA and LHC data. In light of the upcoming upgrades to the LHC, the dependence of our results on rapidity will also be discussed.

Dr. Jim Zickefoose and Dr. Gabriela Ilie, Senior Scientists, Physics Division, Mirion Technologies, Meriden CT

Mirion Technologies – Connecting Academia and Industry

Mirion Technologies is a world leader in the development and supply of nuclear instrumentation and supporting software. To accomplish its goals and objectives, Mirion has a diverse team of physicists holding various levels of degrees. In this seminar we will show our paths from graduate studies to joining Mirion, emphasizing how the skills we gained during our academic journeys have contributed or have been beneficial to our professional development in industry. Furthermore, we will highlight Mirion Technologies’ general areas of interest as well as revealing some interesting applications where we have partnered with academia.

Speakers’ bio:

Gabriela is the Product Line Manager for Specialty Detectors and a Senior Application Scientist at Mirion Technologies, focused on developing custom high-purity germanium (HPGe) detector solutions for challenging and unique applications. She joined Mirion in 2012 (formerly Canberra Industries) as a physicist and has worked on a variety of projects offering physics support and doing validation and testing for different products. Gabriela has a Ph.D. in Experimental Nuclear Physics from the University of Cologne, Germany. Before joining Mirion, Gabriela held a Postdoctoral Research position at Yale University where she helped maintain and use a large array of HPGe Clover detectors for nuclear physics measurements and experiments. In the last few years, she has played an active role in promoting new technologies that help customers select the best radiation detection and instrumentation for their applications.

Jim Zickefoose is a Sr. Scientist and R&D Physics Manager at Mirion Technologies in Meriden CT. In these roles he concentrates on driving new technology development across the various Mirion divisions and incorporating those technologies in new or existing products. He joined Mirion in 2010 directly after earning a PhD in physics from the University of Connecticut with a concentration in experimental nuclear astrophysics. During his PhD research Jim studied carbon fusion reactions at accelerator facilities in Caserta, Italy and Bochum, Germany. Prior to his time at UConn Jim earned an Honors Degree in physics from the University of Adelaide.

Note: coffee and cookies at 3:00 outside the lecture room.

Prof. Niloy Dutta, Department of Physics, University of Connecticut

All Optical Correlator

Prof. Geoff Potvin, FIU

UConn physics departmental colloquium

Title and abstract: TBD

Prof. Jason Hancock, Department of Physics, University of Connecticut

Introduction to inelastic X-ray scattering

Prof. Lance Dixon, Stanford University

The DNA of Particle Scattering

Scattering amplitudes are the arena where quantum field theory meets particle experiments, for example at the Large Hadron Collider where the copious scattering of quarks and gluons in quantum chromodynamics (QCD) produces Higgs bosons and many backgrounds to searches for new physics. Particle scattering in QCD and other gauge theories is far simpler than standard perturbative approaches would suggest. Modern approaches based on unitarity and bootstrapping dramatically simplify many computations previously done with Feynman diagrams. Even so, the final results are often highly intricate, multivariate mathematical functions, which are difficult to describe, let alone compute. In many cases, the functions have a “genetic code” underlying them, called the symbol, which reveals much of their structure. The symbol is a linear combination of words, sequences of letters analogous to sequences of DNA base pairs. Understanding the alphabet, and then reading the code, exposes the physics and mathematics underlying the scattering process, including new symmetries. For example, the two scattering amplitudes that are known to the highest orders in perturbation theory (8 loops) are related to each other by a mysterious antipodal duality, which involves reading the code backwards as well as forwards. A third scattering amplitude, which contains both of these as limits, has an antipodal self-duality which “explains” the other duality. However, we still don’t know `who ordered’ antipodal (self-)duality, or what it really means.

Dr. Ming Li

UConn Physics Colloquium

Title and abstract: TBD

Prof. Carlos Trallero, Department of Physics, University of Connecticut

Dynamics at quantum time scales

Prof. Ilya Sochnikov, Department of Physics, University of Connecticut

Quantum Sensors for Quantum Materials Research

Graduate student Dharma Basaula, Department of Physics, University of Connecticut

Dr. Christopher Hayward, Center for Computational Astrophysics, Flatiron Institute

Solving the puzzle of galaxy formation

Understanding the physics of galaxy formation has been a central goal of astrophysics for decades, but we have yet to solve this complicated problem. I will describe what makes understanding galaxy formation so challenging. I will detail how theorists work to decipher this puzzle using numerical simulations, highlighting the key physical processes involved. I will then discuss the idea of ‘forward modeling’, i.e. predicting synthetic observables from hydrodynamical simulations in order to more directly confront theory and observation, and highlight some recent important results of such work.

Speaker’s biography and background

Prof. Erin Scanlon, Department of Physics, University of Connecticut

An Introduction to Physics Education Research

Physics education research (PER) is a subfield of physics that focuses on investigating questions such as: 1) how can we teach physics better?; 2) how do students learn physics?; and 3) how can we make the physics community more inclusive, equitable, and diverse? In this talk, we will give an introduction to PER, including common misconceptions, methods, and the PER happening at UConn.

Graduate student Bochao Xu, DEpartment of Physics, University of Connecticut

Scanning SQUID Investigation of Time-reversal Symmetry Breaking in Exotic Quantum Materials

Spontaneous breaking of time-reversal symmetry in condensed matter systems arises from correlated electronic arrangements leading to various quantum phenomena, such as ferromagnetism, unconventional superconductivity, and topological states of matter. However, these underlying electronic orders are often difficult to detect experimentally if the magnetism associated with the time reversal symmetry breaking is weak. In such cases, the subtle magnetization and complex domain structure call for investigation by experimental techniques with both high magnetic sensitivity and high spatial resolution. In this dissertation talk, I will discuss my exploration of time-reversal symmetry breaking in two systems: a magnetic Weyl semimetal and a Kagome material detected using scanning superconducting quantum interference device (SQUID) microscopy. Both materials exhibit intriguing magnetic structures which were not detectable by the bulk measurements. We show that the Weyl semimetal hosts a tunable heterogeneous domain structure that is likely linked to its unconventional electronic properties. Additionally, our local probe reveals a ferromagnetic-like state in the Kagome material system, contributing evidence to the highly controversial problem within the community regarding the existence of time-reversal symmetry breaking and its underlying mechanism in this material. These results highlight the significance of quantum sensing in advancing the frontier of new correlated materials, and showcase these materials as an ideal playground for studying the magnetism-electrons interplay.

Dr. Jon Curtis, UCLA

Multimode cavity control of ferroelectric fluctuations

Electromagnetic cavities and metamaterials have been used to great effect in the field of AMO physics and electrical engineering. By shaping the spatial, spectral, or polarization characteristics of the electromagnetic environment, the coherent interaction between light and matter can be focused and amplified, leading to phenomena such as lasing, the Purcell effect, the Casimir effect, and superradiance. In this talk I will show how these ideas may be extended and applied to solid state quantum materials. In particular, I will consider polarization fluctuations in a quantum paraelectric insulator, and consider their coupling to a Fabry-Perot type optical cavity. By using the full multimode continuum description of the system, I will show how the ferroelectric fluctuations respond in a local, spatially resolved manner. The presence of the cavity indeed is shown to renormalize the soft-mode frequency, with effects primarily confined to the surface, and thus for thin films this effect can be pronounced. The temperature dependence shows this effect only onsets at low temperatures, indicating its origin from quantum electrodynamics effects – in close analogy with the Casimir effect.

Prof. Alan Wuosmaa, Department of Physics, University of Connecticut

Exotic Nuclei - What are they, how do we study them and why we should care

Just over one hundred years after their discovery by Rutherford, the nuclei of atoms are the focus of considerable renewed interest. Only about 300 nuclear isotopes are stable and can be found in nature, but nearly 3000 nuclei that are stable with respect to proton or neutron emission have been artificially produced in the laboratory. Our understanding of the behavior of the nucleus has largely been guided by ideas developed by studying the nuclei that are stable, however for unstable nuclei with a very large imbalance between protons and neutrons (so-called “exotic nuclei”), these ideas are proving insufficient. The experimental data needed to refine our understanding of the nucleus can only be obtained by performing reactions with short-lived radioactive nuclei. Experiments with such beams are difficult, and introduce many technical challenges. The data they can provide, however, are important not only to understanding nuclear structure, but many other situations such as the violent environments found in exploding stars in the cosmos. I will discuss some of the background behind studies of the structure of exotic nuclei, some modern experimental methods, and prospects for the future.

Prof. Alicia Kollár, University of Maryland

Lattices in Circuit QED

The field of circuit QED has emerged as a rich platform for both quantum computation and quantum simulation. These systems exhibit a high degree of both spatial and temporal control which can be used to create synthetic lattice systems. Spatial lattices can be formed using periodic arrays of resonators. Combined with strong qubitphoton interactions, these systems can be used to study dynamical phase transitions, many-body phenomena, and spin models in driven-dissipative systems. I will show that lattices of coplanar waveguide (CPW) resonators permit the creation of unique devices which host photons in curved spaces, gapped flat bands, and novel forms of qubit-qubit interaction [1,2]. I will show that graph theory is the natural language for describing these microwave photonic systems and present preliminary data on the development of a new generation of CPW lattice devices with unconventional band structures. Periodic modulation in superconducting-qubit systems also provides a route to Floquet systems with topological band structures. I will present preliminary experimental steps toward the realization of a topological energy pump which can “boost” smaller non-clalssical states of light into larger ones [3].

[1] A. J. Koll´ar et al., Nature 45, 571 (2019).

[2] A. J. Koll´ar et al., Comm. Math. Phys. 376, 1909 (2020).

[3] D. Long et al., Phys. Rev. Lett. 128, 183602 (2022).

Dr. Edwin Pedrozo, MIT

Quantum Sensors and the Search for New Physics

The continuously improving performance of quantum sensors is enabling the exploration of fundamental physics with unprecedented precision. Notable examples of these systems include optical atomic clocks and atom interferometers, which are among the most precise devices ever invented by humankind. As a result, they are increasingly utilized in the search for new physics. The application of Atomic, Molecular, and Optical (AMO) Physics techniques to such inquiries in the realm of nuclear physics has been gaining attention in the current decade. The level of control and precision achievable in AMO tabletop experiments, especially with ultracold atoms, enhances the measurement capabilities in complex experimental systems that pursue tests of fundamental physics and symmetries, the search for the electron electric dipole moment (eEDM), and physics beyond the standard model. In this talk, I will explain how incorporating entanglement into these systems can further improve their measurement capabilities. Additionally, I will discuss several proposals that employ laser-cooled atoms and molecules in the search for physics beyond the Standard Model.

Prof. Roopali Kukreja, UC Davis

Imaging ultrafast and ultrasmall: Unraveling nanoscale electronic and magnetic behavior using time-resolved x-ray scattering

Ultrafast laser control of correlated materials has emerged as a fascinating avenue of manipulating magnetic and electronic behavior at femtosecond timescales. Ultrafast manipulation of these materials has also been envisioned as a new paradigm for next generation memory and data storage devices. Numerous studies have been performed to understand the mechanism underlying laser excitation. However, it has been recently recognized that spatial domain structure and nanoscale heterogeneities can play a critical role in dictating ultrafast behavior. In this talk, I will discuss methods and our recent results which capture material behavior at nanoscale lengthscales and femtosecond-nanosecond timescales. I will describe our recent experimental studies using emerging synchrotron techniques and free electron laser such as European XFEL and FERMI. In the first part of my talk, I will discuss our results on ultrafast magnetization dynamics where we uncovered a symmetry-dependent behavior of the ultrafast response. Labyrinth domain structure with no translation symmetry exhibit an ultrafast shift in their isotropic diffraction peak position that indicates their spatial rearrangement. On the other hand, anisotropic domains with translation symmetry do not exhibit any modification of their anisotropic diffraction peak position. In the second part of my talk, I will focus on x-ray imaging of correlated oxides and discuss spatially dependent ultrafast response observed in complex oxides such as rare-earth nickelates. These intriguing observation suggests preferential, texture-dependent paths not only for the transport of angular momentum, but also for structural rearrangements. These measurements provide us with a unique way to study and manipulate spin, charge and lattice degrees of freedom.

Speaker’s bio: Roopali Kukreja joined Materials Science and Engineering department at UC Davis as an Assistant Professor in Fall 2016. She received her B.S. in Metallurgical Engineering and Materials Science from the Indian Institute of Technology Bombay in 2008 and then her M.S. and Ph.D. degrees in Materials Science and Engineering from Stanford University in 2011 and 2014, respectively. Prior to her appointment at UC Davis, Kukreja worked as a postdoctoral researcher at the UC San Diego, with Profs. Oleg Shpyrko (Physics Department) and Eric Fullerton (Center for Magnetic Recording Research). Her research interests at UC Davis focuses on ultrafast dynamics in nanoscale magnetic and electronic materials, time resolved X-ray diffraction and imaging techniques, thin film deposition and device fabrication.

Prof. Gerald Dunne, Department of Physics, University of Connecticut

Scientific Communication

I will discuss the problem of preparing a scientific presentation (a paper, a talk, a proposal, …). This is a valuable skill that all aspiring scientists should make the effort to learn. It is difficult, but it is both valuable and enjoyable, and well worth the effort.

Prof. Steve Lamoreaux, Yale University

Title: TBA

Prof. Anh-Thu Le, Department of Physics, University of Connecticut

Atoms and molecules in ultrafast intense lasers: from femtosecond to attosecond timescales

Recent progress in laser technology has led to new coherent light sources that can be used to investigate ultrafast processes in matter. To take advantage of these new light sources, different experimental techniques have been developed to reveal the inner-workings of coupled electron-nuclear dynamics in molecules. Concurrently, theoretical and computational tools have also been developed to understand and decode hidden information from experimental measurements. In this talk, I will present our group’s recent progress in understanding intense laser-atom/molecule interactions by using some of the most promising techniques such as laser-induced electron diffraction, high-harmonic generation spectroscopy, and attosecond transient absorption spectroscopy. Throughout the talk, I will also address the challenges and opportunities in this field for practical realization of molecular “movies” with atomic resolution in space and time that can provide new insights into fundamental chemical reactions.

Prof. Tigran Sedrakyan, University of Massachusetts Amherst

Moat-band physics and emergent excitonic topological order in correlated electron-hole bilayers”

The role of the particle-particle interaction becomes increasingly important if the spectral band structure of a free system has increasing degeneracy. Ultimately, it will be the role of interactions to choose the state of the system. Examples include the systems with the lowest band having a degenerate minimum along a closed contour in the reciprocal space – the Moat. Any weak perturbation can set a new energy scale describing the state with qualitatively different properties in such a limit of infinite degeneracy. In this talk, I will discuss the general principles behind the universal properties of correlated bosons on moat bands, which host topological order with long-range quantum entanglement. In particular, I will discuss moat-band phenomena in shallowly inverted InAs/GaSb quantum wells, where we observe an unconventional time-reversal-symmetry breaking excitonic ground state under imbalanced electron and hole densities. I will show that the strong frustration of the system leads to a moat band for excitons, resulting in a time-reversal-symmetry breaking excitonic topological order, which explains all our experimental observations.

Daniel Norman, Department of Physics, University of Connecticut

The Complex Analytic Properties of Bandwidth Limited Signals and their Application to Conformal Cosmology and Signal Processing

Conformal gravity is an alternative theory of gravity derived from the conformally invariant Weyl squared action as opposed to the standard Einstein-Hilbert action. The general equations of conformal gravity were applied to the cosmological scale to create a theory of Conformal Cosmology where the geometry of space-time is described by first order fluctuations on a conformal-to-flat background of constant negative curvature. The differential equations of this cosmological model have solutions in terms of Legendre functions with complex degree and order. In order to calculate the multipole expansion of Cosmic Background Radiation (CMB) anisotropy within this model, it is necessary to integrate the Legendre function solutions with respect to their complex degree. An analytic method for solving this integration problem was developed which makes use of the fact that the Legendre functions are Bandwidth Limit Signals (BLS’s) which are functions with a finite domain in frequency space. A general analysis of the properties of BLS’s in the complex plane was done which has yielded new theorems and expansion formulas applicable to all BLS’s as well as to other related families of complex functions. These results have both specific applications to Conformal Cosmology as well as broader applications to the field of signal processing. The methods of complex integration developed in this work, initially for the purpose of computing the CMB anisotropy in Conformal Cosmology, have been used to provide a novel solution to the infamous Borweinn integral as well as a novel proof of the Nyquist-Shannon sampling theorem.

Prof. Abhay Pasupathy, Columbia University and Brookhaven National Laboratory

We understand that the phenomenon of superconductivity involves the formation of pairs of electrons that find a way to attract each other in a solid. We also know that in most known superconductors, pairs of electrons are formed between two electrons that have opposite momentum and spin. A magnet, on the other hand, is a material where there is a dominance of electrons of one spin with respect to the other. What happens if we put these two phenomena together in a single material? Such is the case in the curious compound EuRbFe4As4, which displays superconducting order at a temperature of 35 K, and displays magnetic order at a lower temperature of 16 K. In this compound, superconductivity lives in atomic planes of FeAs, while the magnetism lives in adjacent layers of Eu. Electrons can jump from from one layer to the other, coupling the superconducting and magnetic properties to each other. I will describe scanning tunneling microscopy measurements that probe the consequences of this coupling, including the formation of superconducting order that is modulated in space, as well as an unusual set of excitations that exist in the magnetic superconducting state.

Prof. Daniel McCarron, Department of Physics, University of Connecticut

Laser-cooled molecules for quantum science and controlled organic chemistry

Laser-cooling and trapping techniques for molecules promise access to a diverse range of ultracold species for applications such as quantum computing and improved precision measurements. In this talk, I will present recent progress from two experiments within my group to laser-cool and trap two different species for complementary studies of molecule-molecule interactions. The first, AlCl, has an electronic structure analogous to that of alkaline earth atoms and presents a number of advantages for realizing large, dense samples of laser-cooled molecules. The second, CH, has traditionally been a challenging molecule to produce at high density but offers access to studies of simple controlled organic chemistry that may be compared to calculations by quantum chemists.

Professor Chii-Dong Lin, Kansas State University

Post-Nobel Award on attosecond Science – Challenges and opportunities in the field going forward

It is an exciting month for the attosecond and strong-field physics communities after the announcement of the three Nobel Laureates earlier. How will this field evolve going forward? While it is very attractive to talk about the shortest light pulses to the general public, and even to the physical science community, the field still faces great challenges but also opportunities. I will “talk” about the challenges and will share with you some of the recent progress toward developing theories that can be compared to experiments.

Prof. Cyrus Dreyer, Stony Brook University and Flatiron Institute

Nonadiabatic lattice dynamics in metals and magnets

In electronic structure theory, lattice vibrations are usually treated under the Born-Oppenheimer approximation, where electronic degrees of freedom are assumed to be fast compared to nuclear dynamics. However, going beyond this adiabatic approximation is necessary in many situations for an accurate description of phonons, and their effects on materials properties. I will discuss two such cases. The first case involves Born effective charges, which are crucial to understanding, e.g., ferroelectric polarization, phonon dispersions in ionic insulators, electron-phonon scattering, dielectric screening, electromechanical coupling, and optical spectra in the IR/THz regime. Via density-functional perturbation theory (DFPT) calculations, I will show that going beyond the adiabatic approximation extends the definition of Born effective charges from insulators to conducting systems and relates them to a seemingly unrelated fundamental property of metals: the Drude weight. The second case I will discuss is the coupling of magnetism and phonons in materials. Specifically, I will demonstrate a DFT-based methodology for including the velocity-dependence of interatomic forces, which explicitly accounts for time-reversal symmetry breaking in the nuclear equations of motion. I will show that in some magnetic materials, such as CrI3, the assumption of adiabatic separation between electron and nuclear dynamics breaks down completely due to the role of (slow) spin dynamics in the coupling between phonons and the magnetic order.

Gérard Mourou, École polytechnique Palaiseau France

PASSION EXTREME LIGHT AND APPLICATIONS TO THE GREATEST BENEFIT OF HUMAN KIND 

Extreme-light laser is a universal source providing a vast range of high energy radiations and particles along with the highest field, highest pressure, temperature and acceleration. It offers the possibility to shed light on some of the remaining unanswered questions in fundamental physics like the genesis of cosmic rays with energies in excess of 1020 eV or the loss of information in black-holes. Using wake-field acceleration some of these fundamental questions could be studied in the laboratory. In addition extreme-light makes possible the study of the structure of vacuum and particle production in “empty” space which is one of the field’s ultimate goal, reaching into the fundamental QED and possibly QCD regimes. Looking beyond today’s intensity horizon, we will introduce a new concept that could make possible the generation of attosecond-zeptosecond high energy coherent pulse, de facto in x-ray domain, opening at the Schwinger level, the zettawatt, and PeV regime; the next chapter of laser-matter interaction.

Dr. Romain Vasseur, University of Massachusetts  Amherst

Learning global charges from local measurements

Monitored random quantum circuits (MRCs) exhibit a measurement-induced phase transition between area-law and volume-law entanglement scaling. In this talk, I will review the physics of such entanglement transitions, and discuss the current status of this field as well as recent experimental realizations. I will argue that MRCs with a conserved charge additionally exhibit two distinct volume-law entangled phases that cannot be characterized by equilibrium notions of symmetry-breaking or topological order, but rather by the non-equilibrium dynamics and steady-state distribution of charge fluctuations. These include a charge-fuzzy phase in which charge information is rapidly scrambled leading to slowly decaying spatial fluctuations of charge in the steady state, and a charge-sharp phase in which measurements collapse quantum fluctuations of charge without destroying the volume-law entanglement of neutral degrees of freedom. I will present some statistical mechanics description of such charge-sharpening transitions, and relate them to the efficiency of classical decoders to “learn” the global charge of quantum systems from local measurements.

Dr. Sandra Beauvarlet, UConn and PULSE, SLAC National Laboratory

Attosecond X-ray pulse pair generation at SLAC- LCLS X-ray Free Electron Laser and application to probe ultrafast electron dynamics in aminophenol

I will present in this AMO seminar general notions about how Free Electron Laser (FEL) work and will present some of the characteristics and more recent developments at the SLAC X-ray FEL light source. I will discuss the key advances to reach the sub-fs timescale enabling the production of isolated attosecond X-ray pulses but also the generation of attosecond X-ray pulse pairs with controllable delays. These pulses open the way to pump-probe measurements of ultrafast dynamics with attosecond temporal resolution and angstrom spatial resolution due to the X-ray nature of the light produced. Going from a more technical development perspective to an experimentalist vision, I will report on two examples of attosecond X-ray pump - attosecond X-ray probe measurements conducted on gas phase Aminophenol molecules (C ₆ H ₇ NO). The first one relies on carbon K-shell ionization and the effect of post-collision interaction (PCI). The second one relies on X-ray absorption spectroscopy to probe charge migration across the molecules on a sub-10 fs timescale.

Prof. Nora Berrah, Department of Physics, University of Connecticut

Probing Molecular Dynamics in Real Time with Fancy, Ultrafast Lasers

The knowledge of the earliest time dynamics in molecular photo-physics are critical because their role is to harness the energy from photons, initiating electronic and nuclear motion, which is fundamental in many areas of science. The ultimate goal of my research program is to understand the coupled electronic and nuclear dynamics induced by the absorption of photons by molecules, which leads first to attosecond electron excitation within the molecules, which is the topic of the 2023 Nobel Prize. This electronic motion is followed by nuclear motion in the molecule in the femtosecond range. This ultrafast dynamics eventually results in the breaking and making of chemical bonds on the picosecond timescale.

I will present the research we conduct in my UConn Laser Lab as well as describe research using X-ray lasers. The past decade has seen the exciting birth of the first X-ray laser, the LCLS free electron laser (FEL)at SLAC National laboratory followed by other FELs around the world, leading to an explosion of new science, in the femtosecond and very recently in the attosecond timescale regime.

Prof. Simone Colombo
University of Connecticut

Title: Quantum Metrology with Ultracold Atoms (and Optical Cavities)

Abstract:

In this colloquium, I will introduce the application of atomic, molecular, and optical (known as AMO) physics to the field of quantum metrology. I will show how atoms are used as probes of our universe and how to harness quantum effects to enhance their sensing capabilities.

I will then focus on a specific type of atomic sensor and one of my research interests: optical atomic clocks. State-of-the-art optical atomic clocks achieve mind-boggling stabilities and in many regimes are almost solely limited by quantum noise. Building upon recent results (mine and from other groups), I will illustrate how optical clocks’ performances can be pushed beyond current quantum noise limitations and how they can be/are deployed in the search for new physics and the testing of the fundaments of general relativity. Within this framework, I will finally overview the research activities I am developing at UConn.

Prof. Jason Hancock, Department of Physics, University of Connecticut

Condensed matter and applied physics at UConn

In this talk, I hope to help contextualize the scientific and social importance condensed matter physics plays in our world, the nation, in our department, and in our research group. This broad survey aims to assess to introduce some exciting modern topics and will hopefully help you understand what opportunities exist in a very collaborative field with exciting opportunities.

Dr. Abhishek Bannerjee, Harvard University

Dr. Heide Ibrahim, INRS, Canada

Filming ultrafast chemical reactions in real-time – from coherent motion to roaming dynamics

Upon photoexcitation, molecules can undergo different types of transformations such as simple vibrations or rotations, but also migrations, or dissociations. Due to the required combination of ultrafast time-scales and ultra-small length-scales involved, specific tools are required to follow such reactions in real-time. Here, we are using time-resolved Coulomb explosion imaging (CEI) as the ultrafast tool to image such dynamics. With CEI, we can not only image coherent molecular dynamics such as proton migration in acetylene; it also works for various dissociation pathways, even if they occur differently from one molecule to another.

In the formaldehyde molecule, we can see fragments following the direct, conventional dissociation path, as well as fragments deviating from this minimum energy path. So-called roaming fragments or “roamers” explore the potential energy landscape in a statistical manner and were directly captured in real-time, despite the signal’s statistical character. This is possible due to the single-molecule sensitivity of CEI. In addition to the first direct observation of roaming fragments undergoing dynamics, we could show that the onset of roaming occurs actually several orders of magnitude earlier than previously expected. We thus show that CEI provides the means to extract new, unexpected pathways, which would otherwise remain hidden underneath a strong background.

Provakar Datta, Department of Physics, University of Connecticut

Probing the Neutron’s Internal Structure via High-Q2 Electromagnetic Form Factor Measurements

The electromagnetic form factors (EMFFs) are among the most basic observables sensitive to the nucleon’s internal structure. Knowing their values with high precision in a wide range of squared four-momentum transfer (Q2) is essential for the advancement of QCD. The high Q ² precision data of the nucleon EMFFs are scarce due to the challenges associated with such measurements. However, the Super BigBite Spectrometer (SBS) collaboration is currently running multiple experiments in Jefferson Lab’s experimental Hall A to precisely measure the proton and neutron EMFFs with unprecedented Q ² reach, which will vastly improve the situation. In this talk, I will give an overview of the SBS high Q ² program with a focus on the SBS-GMn experiment. SBSGMn, the very first SBS experiment, was completed during Oct. 2021 - Feb. 2022 running period to measure the neutron magnetic form factor (GnM) up to Q ² = 13.6 (GeV/c) ² using “ratio” method. I will briefly discuss the underlying theory, measurement technique, associated technical challenges, and present our progress of physics analysis including preliminary data/MC comparisons. I will also show realistic projections of the final uncertainties on GnM, emphasizing the high-Q ² data points.

Prof. Moshe Gai, Department of Physics, University of Connecticut

Precision Stellar Evolution

Research at the Laboratory for Astrophysics at Avery Point (aka Laboratory for Nuclear Science), is involved with measurements of critical reaction in the various stages of Stellar Evolution. We aim to develop in house at our Lab at Avery Point, detector technologies that allow us to address central issues in the burning stages of a star. In particular we developed a Time Projection Chamber (TPC) detector that we used to address the formation of oxygen in Stellar Helium Burning [1]; a well-known central problem in stellar evolution. We will review Stellar Evolution theory, Detector R&D and our latest results.

[1] “Precision measurement on oxygen formation in stellar helium burning with gamma-beams and a TPC detector”, R. Smith, M. Gai, S. R. Stern, D. K. Schweitzer, M. W. Ahmed, Nature Communications 12, 5920 (2021),

Prof. Chris Laumann, Boston University

Condensed-matter systems provide alternative “vacua” exhibiting emergent low-energy properties dramatically different from those of the standard model. A case in point is the emergent quantum electrodynamics (QED) in the family of magnetic materials known as quantum spin ice. The emergent QED possesses many features familiar from our universe, such as charges, anti-charges and photons, but also
many unfamiliar one, such as magnetic monopoles. Thus these magnetic insulators provide a laboratory for exploring effective QED in regimes quite inaccessible to traditional Maxwell electromagnetism.

In this talk, I will review the beautiful picture of how QED emerges in these frustrated magnets when quantum fluctuations cause the spins to fractionalize into spinons – and what this has to do with ice and pyrochlore materials. We will then turn to several results regarding its fine structure. We will see that the fine structure constant – the dimensionless coupling which controls the interactions between
emergent light and charges – generically takes values ~0.1 in quantum spin ice, much larger than the \(\alpha\) ~ 1/137 of our universe [1]. This leads to a variety of predictions regarding the coherent dynamics of the spinons which we expect can be probed by neutron scattering [2]. Finally, we will consider how true electric fields couple into this magnetic insulator – and may permit the indirect observation of
the emergent magnetic monopole and a curious inverted Lorentz force [3].

[1] Pace, Morampudi, Moessner, Laumann. Phys. Rev. Lett. 127, 117205 (2021).
[2] Morampudi, Wilczek, Laumann. Phys. Rev. Lett. 124, 097204 (2020).
[3] Laumann, Moessner. arXiv:2302.06635.

Shaswat Tiwari, NCSU 

Entanglement measures in scattering and the S-matrix Bootstrap

Quantum information theory has been instrumental in offering new
insights into old physics problems. In this talk, I shall use it to
study 2-2 scattering in quantum field theories[1], defining the
Entanglement entropy and the relative entropy in this setting. I will
evaluate these measures for theories like φ4, chiral perturbation
theory ( χP T ), etc. Using known bounds on the differential elastic
cross section, I will argue a general bound on relative entropy at
high energy. I will also find definite sign properties of relative
entropy that shall help constrain the S-matrix Bootstrap. Reviving the
old 1960s effort to study Quantum field theory using S-matrices, the
S-matrix bootstrap is a recent attempt to study S-matrices
numerically. I will briefly describe the bootstrap methods and how
relative entropy becomes helpful in this study. These constraints help
isolate S-matrices, which have leading Regge trajectory compatible
with experiments[2].


[1] A. Bose, P. Haldar, A. Sinha, P. Sinha, and S. S. Tiwari,
“Relative entropy in scattering and the
S-matrix bootstrap,” SciPost Phys. 9, 081 (2020),arXiv:2006.12213 [hep-th]

[2]A. Bose, A. Sinha, and S. S. Tiwari, “Selection rules for the
S-Matrix bootstrap,” SciPost Phys. 10, 122 (2021),arXiv:2011.07944
[hep-th].

Prof.  Andrew Puckett, Department of Physics, University of Connecticut

Precision studies of proton and neutron structure via medium-energy electron scattering

Electron scattering has been one of the most important tools for precisely probing the femtoscopic structure of strongly interacting matter ever since Hofstadter’s pioneering measurements of electron-proton scattering and electron-nucleus scattering at Stanford in the 1950s revealed the non-point-like nature of the proton and provided a first measurement of the proton’s size, leading to the Nobel Prize in Physics in 1961. The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLab) in Newport News, Virginia, is the world’s leading facility for the precision three-dimensional imaging of the nucleon’s quark-gluon structure in both coordinate and momentum space. CEBAF uses superconducting radio-frequency acceleration technology to deliver electron beams of unparalleled quality in terms of energy, intensity, duty-cycle, and polarization. Experimentalists use these high-quality electron beams together with state-of-the-art target and detector technologies and high-performance data acquisition and computing capabilities to map the internal structure of strongly interacting matter with unprecedented precision and kinematic reach. In this talk, I will give a brief overview of the physics of electron scattering and its usefulness as a precision probe of nuclear structure, followed by a detailed overview of UConn’s role and Ph.D. research opportunities at JLab with the Puckett group.

Dr. Oleg Gorobtsov, Cornell University

In quantum materials, coexistent degrees of freedom such as spin, charge, and lattice respond in concert to various external stimuli including light and electrical current. Understanding the interactions between these degrees of freedom and stimuli promises advances in technology from next-generation electronics to energy storage. From coexistent emergent phases and far-from-equilibrium states to topological defects and nanomaterial morphology, nanostructural heterogeneities in space and time connected to crystal lattice commonly underpin the material behavior. Breakthrough coherent X-ray scattering techniques at novel X-ray sources capture nanoscale changes in lattice in-situ to connect them to macroscopic properties. Precise control over lattice dynamics by photoexcitations on sub-picosecond timescales sheds light on interaction between lattice dynamics and electronic order in chromium, an archetypal density wave material. In Mott insulators, nanoscale measurements reveal novel hierarchy and transition behavior of heterogeneities during metal-insulator transitions. Unique capabilities of coherent X-ray science offer us glimpses into the physics of phase transition in quantum materials and future design possibilities.

Prof. George Gibson, Department of Physics, University of Connecticut

The influence of molecular structure on strong-field interactions and the problem of coupling three electrons

1D 1-electron models explain a surprising amount of phenomena in the strong-field interaction with atoms and molecules, such as ionization rates, enhanced ionization at a critical internuclear separation, and high-harmonic generation. 1D 2-electron models predict multielectron phenomena, such as enhanced multiphoton susceptibilities leading to strong multiphoton excitation. In this talk, we examine 1D 3-electron systems to address the possibility of direct inner-orbital ionization. Indeed, an old question of excitation through inner-orbital ionization, versus a two-step process, in which ionization is followed by excitation can finally be answered. Based on symmetry arguments, we show unambiguously that direct inner-orbital ionization is possible.

Prof. P. Mannheim, Department of Physics, University of Connecticut

Normalization of the vacuum and the ultraviolet completion of Einstein gravity

Second-order-derivative plus fourth-order-derivative gravity is the ultraviolet completion of second-order-derivative quantum Einstein gravity. While it achieves renormalizability through states of negative Dirac norm, the unitarity violation that this would entail can be postponed to Planck energies. As we show in this paper the theory has a different problem, one that occurs at all energy scales, namely that the Dirac norm of the vacuum of the theory is not finite. To establish this we present a procedure for determining the norm of the vacuum in any quantum field theory. With the Dirac norm of the vacuum of the second-order-derivative plus fourth-order-derivative theory not being finite, the Feynman rules that are used to establish renormalizability are not valid, as is the assumption that the theory can be used as an effective theory at energies well below the Planck scale. This lack of finiteness is also manifested in the fact that the Minkowski path integral for the theory is divergent. Because the vacuum Dirac norm is not finite, the Hamiltonian of the theory is not Hermitian. However, it turns out to be PT-symmetric. And when one continues the theory into the complex plane and uses the PT-symmetry inner product, viz. the overlap of the left-eigenstate of the Hamiltonian with its right-eigenstate, one then finds that for the vacuum this norm is both finite and positive, the Feynman rules now are valid, the Minkowski path integral now is well behaved, and the theory now can serve as a low energy effective theory. Consequently, the theory can now be offered as a fully consistent, unitary, and renormalizable theory of quantum gravity.

Prof.  Simone Colombo, Department of Physics, University of Connecticut

Quantum Metrology with Ultracold Atoms (and Optical Cavities)

In this seminar, I will introduce the application of atomic, molecular, and optical (AMO) physics to the field of quantum metrology. I will show how atoms are used as probes of our universe and how to harness quantum effects to enhance their sensing capabilities.

I will then focus on a specific type of atomic sensor and one of my research interests: optical atomic clocks. State-of-the-art optical atomic clocks achieve mindboggling stabilities and are almost solely limited by quantum noise. Building upon recent results (mine and from other groups), I will illustrate how optical clocks’ performances can be pushed beyond current quantum noise limitations and how they can be/are deployed in the search for new physics and the testing of the fundaments of general relativity. Within this framework, I will finally overview the research activities I plan to develop at UConn and discuss possible career perspectives.

Graduate student Phi-Hung Tran, Department of Physics, University of Connecticut

An accurate semiclassical method for constructing photoelectron momentum distribution for atoms and molecules in intense lasers

We propose a version of the semiclassical method based on the Herman-Kluk propagator combined with the strong-field approximation for atoms and molecules in intense lasers. Here we illustrate the application of the method for calculation of photoelectron momentum distribution (PMD) for different atoms (H, Ar, Ne, and Xe) in intense few-cycle laser pulses. We show that the constructed PMDs agree very well with the exact numerical solutions of the time-dependent Schrödinger equation. We further show that our method provides a clear physical interpretation for the validity of the factorization of the recollision process. In contrast to the common belief that there are two paths, so-called long and short trajectories, we found that there are typically multiple trajectories that lead to a given final momentum in the high-energy region. Accurate phases of those trajectories are needed to obtain correct interference patterns in the PMD. Our method can be used to extend current capabilities of laser-induced electron diffraction and other ultrafast imaging and strong-field spectroscopic techniques.

Prof. Michael Lublinsky, Department of Physics, Ben-Gurion University

Magnetic monopole in chiral plasma

Chiral anomaly induces qualitatively new transport phenomena in finite temperature plasma of massless fermions. In the first part of the talk, we will explore the effect of a magnetic monopole inserted into chiral plasma. Next, we will present various novel anomaly induced phenomena discovered in a holographically defined model.

Graduate student Hanzhen Ma, Department of Physics, University of Connecticut

Cooperative radiation has been a long-standing open question in many-body physics. The dipole-dipole interaction between the atoms gives rise to the all-to-all coupling, and can lead to novel collective phenomena. In this talk, I will introduce an integrated method for studying cooperative radiation in many-body systems. This method allows us to study extended systems with arbitrarily large number of particles, and can be formulated by an effective, nonlinear, two-atom master equation that describes the dynamics using a closed form. We apply this method to various systems to demonstrate the appearance of superradiance, subradiance, collective Lamb shift, spin-squeezing and so on. We investigate how the properties of radiation depend on system parameters such as the optical depth and geometry of the system.  

Prof. P. Volkov, Department of Physics, University of Connecticut

The universe(s) of quantum materials

In my talk I’ll introduce condensed matter research from a theory perspective. I’ll show how the underlying quest to explain material properties led to discoveries of physical concepts of universal significance, such as spontaneous symmetry breaking or topological states and transitions.

I’ll then move to the current topics of active development united under the umbrella term “quantum materials”, focusing on the current topics of my research: 2D materials, interacting electrons in polar metals and ferroelectrics, and emergence of exotic electronic orders. The approaches I use combine analytical quantum field theory methods with phenomenological symmetry-based modeling with a special emphasis on making contact with experiments. Finally, I’ll overview the activities I plan to lead at UConn and discuss career perspectives.

Prof. Matthew Szydagis, Department of Physics, University at Albany SUNY

The First Dark Matter Search Results From the LUX-ZEPLIN (LZ) Experiment

The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in Lead, SD, with significant contributions from UAlbany. I will report on results from LZ’s first search for Weakly Interacting Massive Particles (WIMPs) with an exposure of 60 live-days using a fiducial mass of 5.5 tonnes. A profile-likelihood ratio (PLR) analysis shows the data to be consistent with a background-only hypothesis, setting new limits on spin-independent WIMP-nucleon, spin-dependent WIMP-neutron, and spin-dependent WIMP-proton cross-sections for WIMP masses above 9 GeV/c^2. The most stringent limit is set for spin-independent scattering at 30 GeV, excluding cross sections above 5.9 × 10^-48 cm^2 at a 90% confidence level.

Mitchell Bredice and Vasili Kharchenko, Department of Physics, University of Connecticut

Nano-particles in Atomic Physics, Atmospheric Science, and Astrophysics

Nucleation of nano-size particles and their evolution in specific environments have been intensively studied for several decades. Experimental and theoretical investigations of nucleation processes are the most formidable tasks for researchers from different scientific disciplines, including quantum mechanics, plasma physics, atmospheric science, astrophysics, climate change, and biology. A brief review of our research program on investigations of physical properties of nanoparticles and their nucleation will be presented. Examples of theoretical analysis of nucleation processes in atomic physics, astrophysics, and atmospheric science will be discussed and current research projects will be described.