Join us for UT Physics Honors Day as we recognize outstanding students, faculty, and staff! As the final colloquium of the spring, we’ll move to Room 262 in the Student Union to present our annual awards.

Since the times of Henry Cavendish and John Mitchell, the strength of gravity has been measured by comparing it to the reaction of a calibrated mechanical spring. While in the last 60 years planetary measurements (with natural and artificial bodies) have provided remarkable accuracy at large distance, measurements in the lab have continued to rely various incarnations of the good old mechanical springs, in many cases resulting in superb experiments and results.

In this talk, I will explore a number of drastically different techniques recently developed specifically to tackle the short distance regime, where many theories suggest something exotic may be happening. This will be a trip into AMO, high resolution nuclear spectroscopy, and neutron scattering. While science results are gradually appearing, I hope to convince the audience that, as is often the case with new techniques, a new and exciting array of questions and applications are also emerging!

There will be no physics colloquium on April 21.

The James Webb Space Telescope is the culmination of thirty years of planning, twenty years of construction, and eleven billion dollars of funding — and it was designed specifically to perform the first systematic exploration of stars, galaxies, and black holes in the early universe. Luckily for us, this first systematic exploration is happening now; in our lives. I will discuss some of the early, stunning, and sometimes tentative, discoveries we have made in Webb’s first deep fields, measuring the ancient light from early galaxies and black holes originating near the edge of the observable universe. I will in particular discuss the latest observational constraints on the new, mysterious, very bright, surprisingly common, and so-far-inscrutable objects at the edge of the universe: “little red dots”. Are they overly massive and/or old galaxies, `overmassive` supermassive black holes arising far earlier than expected – or perhaps something else entirely?

Superconductivity and superfluidity are some of the most striking macroscopic manifestations of quantum mechanics. In recent years strong superconductivity has been observed in systems in which the electrons behave as extremely heavy particles, i.e., have a very large effective mass. This is somewhat surprising given that the conventional theory of superconductivity predicts that the ability of a system to carry a supercurrent decreases as the effective mass of the electrons increases. In this talk I will discuss how robust superconductivity and superfluidity can be present in multi-band systems in which the effective mass of the electrons is infinite due to the quantum metric of the electronic states. This contribution is one more example of the deep connection between quantum mechanics and superconductivity. I will then discuss the relevance of this contribution for systems like twisted bilayer graphene.

The era of time domain and multi-messenger astronomy is not only leading to the development of a much broader set of detectors and instruments for astrophysical observations, but is also providing the means for astronomy to tie directly to cutting-edge studies in physics. In this manner, fundamental physics (theory and experiment) coupled with a strong theoretical understanding of astrophysical phenomena (guided by high-performance computing simulations) can tie directly to the amazing new observations in astronomy. Here we discuss how physics, astrophysical models, and observations can not only help astronomy probe fundamental physics but guide the needs for next-generation astrophysical missions.

There are approximately 300 stable and 3,000 known unstable (rare) isotopes. Estimates are that over 7,000 different isotopes are bound by the nuclear force. It is now recognized that the properties of many yet undiscovered rare isotopes hold the key to understanding how to develop a comprehensive and predictive model of atomic nuclei, to accurately model a variety of astrophysical environments, and to understand the origin and history of elements in the Universe. Some of these isotopes also offer the possibility to study nature’s underlying fundamental symmetries and to explore new societal applications of rare isotopes. This presentation will give a glimpse of the opportunities that arise at the Facility for Rare Isotope Beams (FRIB) that started operations at Michigan State University in 2022.

Rapid progress in the experimental control and interrogation of molecules is enabling new opportunities for investigating the fundamental laws of our universe. In particular, molecules containing heavy, octupole-deformed nuclei, such as radium, offer enhanced sensitivity for measuring yet-to-be-discovered parity and time-reversal violating nuclear properties. In this colloquium, I will present recent highlights and perspectives from laser spectroscopy experiments on these species, as well as discuss the relevance of these experiments in addressing open problems in nuclear and particle physics.

In this talk, I will briefly introduce the molecular beam epitaxy (MBE) growth mechanism and then focus on my research, which centers on the MBE growth of quantum materials, spanning from topological materials to interfacial superconductors. I will talk about two solid-state phenomena with zero resistance: the quantum anomalous Hall (QAH) effect and the interface superconductivity. The QAH insulator is a material in which the interior is insulating but electrons can travel with zero resistance along one-dimensional conducting edge channels. Owing to its resistance-free edge channels, the QAH insulator is an outstanding platform for energy-efficient electronics and spintronics as well as topological quantum computations. With many efforts, we were the first to realize the QAH effect in MBE-grown Cr- and V-doped topological insulator (TI) thin films. I will briefly talk about the route to the QAH effect and then focus on our recent progress on the high Chern number QAH effect and three-dimensional QAH effect in MBE-grown magnetic TI multilayers. Finally, I will talk about the interfacial superconductivity in MBE-grown magnetic TI/iron chalcogenide heterostructures. Moreover, the magnetic TI/iron chalcogenide heterostructures fulfill the three essential ingredients of chiral topological superconductivity, i.e. ferromagnetic, topological, and superconducting orders, and thus provide an alternative platform for the exploration of chiral Majorana physics towards the scale topological quantum computations.

Core-collapse supernovae and neutron-star mergers produce copious amount of neutrinos, which impact evolution of these astrophysical sites as well as the element synthesis they may host. Collective oscillations of these neutrinos represent emergent nonlinear flavor evolution phenomena instigated by neutrino-neutrino interactions in astrophysical environments with sufficiently high neutrino densities. In this talk, after a brief introduction, it will be shown that neutrinos exhibit interesting entanglement behavior in simplified models of those oscillations. Also attempts to study this behavior using classical and quantum computers will be described.

My research focuses on understanding the implications of the Standard Model of particle physics in the formation of the basic building blocks of nature. This model describes three of the four fundamental forces of nature. The opaquest of these is the strong nuclear force which is responsible for the formation of all atomic nuclei. We know that this force is fundamentally described in terms of the theory of quarks and gluons, which is known as quantum chromodynamics (QCD). My research focuses on the development and implementation of novel mathematical and computational techniques to study the emergence of nuclear phenomena directly from QCD. In this talk, I review some of the key ideas driving the field of nuclear physics.

Raising the superconducting transition temperature (Tc) to a point where applications are practical remains one of the most critical challenges in condensed matter physics today. Recent advances in sulfur hydrides have renewed hope of reaching room temperature superconductivity, though the extremely high-pressure requirement limits their practical applications. In this talk, I will show our work on an alternative route to achieve high-temperature superconductivity. By the epitaxial growth of single-layer superconductors on tailored substrates, the superconducting Tc can be enhanced through interfacial interactions optimized to enable 1) charge transfer doping and electron-phonon coupling, 2) coupling to quantum fluctuations of the substrate, and 3) dynamic control via light-matter interactions. Using FeSe grown on SrTiO3(001) substrate as an example, I will show that growth on different terminations of the SrTiO3 substrate can enable the control of charge transfer doping and, in turn, superconducting Tc. Similarly, the substitution of isovalent sulfur (S) or tellurium (Te) in FeSe, equivalent to applying positive (negative) chemical pressure, can turn the interfacial atomic-scale geometry that controls the strength of electron-phonon coupling, thus the superconducting Tc. Finally, I will show that UV light can lead to enhanced superconductivity in the FeSe/SrTiO3, which is also persistent. These findings indicate that epitaxial Fe-chalcogenide heterostructures are a highly tunable quantum system and shed light on the mechanism of high-temperature superconductivity in Fe-based superconductors.

The department will share good news and plans for the future, followed by a Q&A session with faculty, staff, and students.

The collision of extremely dense objects such as neutron stars and black holes provides us with a remarkable laboratory to study the laws of physics in extreme environment. Through the study of merging neutron stars, we learn about gravity, the properties of dense matter, the formation of heavy nuclei (gold, platinum, uranium) and neutrino physics. In this talk, I will review the physical processes at play in neutron star mergers and discuss what numerical simulations of colliding neutron stars tell us about the ways in which these systems can be used to better understand cold nuclear matter and astrophysical nucleosynthesis.

Topological quantum computing involves using non-Abelian Majorana zero modes for carrying out error-free fault-tolerant quantum computing. This is the preferred quantum computing platform of Microsoft. I will discuss the current status of the search for non-Abelian Majorana zero modes in solid state systems, discussing both theory and experiment. I will also provide my personal prognosis on what the future holds for the subject.

All cells sense and respond to physical and chemical cues in their environments. They accomplish this through signal transduction systems—networks of interacting proteins that detect and interpret specific input signals and control appropriate cellular responses. In bacteria, these systems are found in remarkable numbers within individual organisms and across different bacterial species. They play a central role in regulating basic aspects of microbial physiology and mediate responses to diverse environmental signals. I will describe work in which we have explored the organization and properties of these networks in the particularly well studied and genetically tractable organism Escherichia coli.

The proton and neutron, known as nucleons, are the fundamental building blocks of all atomic nuclei that make up essentially all the visible matter in the universe, including the stars, the planets, and us. More than 50 years of study has revealed that nucleons are composed of elementary particles called quarks and gluons, whose interactions and dynamics are governed by Quantum Chromodynamics (QCD). However, many profound questions remain. In this talk, I will demonstrate that the newly upgraded CEBAF facility at Jefferson Lab and the future Electron-Ion Collider are two complementary and necessary facilities that are capable of exploring the inner structure of nucleons and nuclei at sub-femtometer distance scale, enabling a new emerging science and technology – Nuclear Femtography. These facilities will help address the most compelling unanswered questions about the elementary building blocks of our visible world, taking us to the next frontier of the Standard Model of physics.

PRX is published by the American Physical Society, a nonprofit membership society of scientists. Its mission goal is to select around 250 *landmark* papers a year from all fields of physics and showcase them to a broad and multidisciplinary readership.

Is your paper a good match for PRX? Or asked differently, what papers qualify as *landmark* papers?

How do the PRX editors actually select such papers? Are such selections always accurate?

How can you, as an author, navigate PRX’s editorial and peer-review process effectively and get the most out of your interactions with the editors and referees?

I will use the talk to discuss with you how to answer these questions. Many of these questions do not have a black-and-white answer in the case of a single paper. Open-minded, reasoned, and constructive dialogues amongst the authors, the editors, and the referees are key to making each concrete process a meaningful and productive experience, and sometimes even a pleasure, for everyone.

Quantum networks have the potential to support capabilities that are unachievable with classical means alone. Besides quantum cryptographic applications, quantum networks have a variety of scientific uses and can help scale up quantum computers. However, the realization of quantum networks faces formidable challenges which include noise that is inflicted upon quantum states, and loss that is suffered by photons which act as information carriers between distributed quantum information processors. In this talk, I will introduce some of the fundamentals of quantum communication, provide examples of noise and loss in quantum systems with real-world examples, and discuss some of the ways that can help us cope with these challenges. At the end of the talk, I will identify several topics that are of research interest to the quantum networks community.

Under specific conditions, exotic Cooper pairing state can emerge with a non-uniform equilibrium order parameter, possessing a finite center-of-mass momentum. Such spatially dependent order parameters (Δ𝑃(r)) can generically feature variations in either their amplitude or phase — or a combination of both. Utilizing Spectroscopic Imaging Scanning Tunneling Microscopy (SI-STM), we’ve identified two primary PDW states in the iron pnictide superconductor, EuRbFe4As4 (ER-1144), a material that features co-existing superconductivity (Tc ≈ 37 kelvin) and magnetism (Tm ≈ 15 kelvin). In the ferromagnetic superconducting phase, the first type is characterized by a superconducting gap that has a long-range, unidirectional spatial modulation (𝛥𝑃~|𝛥0|cos(Q∙r)) in the absence of any other translational symmetry breaking density-wave orders. The second type features an anisotropic Doppler energy shift in reciprocal space due to the phase winding (𝛥𝑃~|𝛥0|𝑒𝑖Q∙r). In contrast, all the striking features are completely suppressed crossing the magnetic transition. Additionally, both PDW states are also impacted by an out-of-plane external magnetic field, evidenced by the Bogoliubov quasiparticle spectrum imaging. Our findings provide valuable insights into the intricate nature of the PDW states and the interplay between magnetism and superconducting order.

Massive stars, by which we mean those stars evolving through all the stable nuclear burning stages, play a fundamental role in the evolution of the Universe. Therefore, a good knowledge of how they evolve is required in order to shed light on many topical subjects like, e.g., the chemical evolution of the galaxies and the nature of the sources of gravitational waves. In the last years three main questions – still debated – rose in the community working on massive stars. They concern (1) the compactness of massive stars at the presupernova stage as an indicator of their explodability, (2) the nature of the remnant after the explosion, and in particular the maximum mass of a stellar black hole, and (3) the so called “Red Supergiant (RSG) problem”, i.e. the lack of observed supernovae associated with the observed most luminous RSGs. In this colloquium I will address these questions by firstly reviewing our current understanding of the presupernova evolution of massive stars.

Fundamental questions in nuclear physics such as, “What is the nature of hot and dense matter?” and “What is the origin of r-process nuclei?” are deeply connected to neutron star observations. In this talk, I will explain how we are answering these questions using a combination of data from nuclear experiments, data from neutron star observations, theoretical models of hot and dense matter, and numerical simulations. Answering these questions demands a level of effort beyond that of a single research group, so I explain how progress is being made through collaborations like the Nuclear Physics for Multi-Messenger Mergers Focused Research Hub. I summarize recent results on both the speed of sound and the composition of dense matter. I show how we are enhancing astrophysical simulations by improving the nuclear physics input. Finally, I show how we are using machine learning to accelerate progress.

The visible world around us is made up of atoms, with protons and neutrons forming the nuclei at their core. Together, protons and neutrons make up most of the mass of everything we see in the universe today, from massive galaxies to individual people. Protons and neutrons themselves are complicated many-body quantum states whose properties are determined by the quarks and gluons that they are comprised of. The quest to understand in detail the structure of protons, neutrons, and nuclei is nothing less that an attempt to answer the questions “What are we made of? What is matter?” The Electron Ion Collider (EIC), to be built by JLab and BNL, will be a unique new machine to collide polarized electrons off polarized protons and light nuclei, providing the capability to study multi-dimensional tomographic images of hadronic matter, and collective effects of gluons in nuclei. In this colloquium I will motivate the physics program at the EIC and the unique new machine and detectors that will be required to answer these fundamental questions.

In the study of quantum matter, measurements have traditionally been viewed as a means of learning about a system. Measurements can, nevertheless, play a more active role—generating novel quantum phenomena that may be difficult or impossible to realize in measurement-free settings. As an interesting example, I will discuss how measurements can dramatically alter universal properties of quantum systems tuned to a phase transition. I will also highlight a path to experimental realization in analog quantum simulators based on Rydberg atom arrays. Finally, I will describe how these ideas inform optimization of quantum teleportation protocols against imperfections—establishing a long-term quantum science application of ‘measurement-altered quantum criticality’.

Symmetry is central to our understanding of natural phenomena. And a Sagnac interferometer, first invented by George Sagnac for the detection of the hypothetical “ether” in the Michelson–Gale experiment [1] a century ago, is intrinsically sensitive to broken time-reversal symmetry (TRS). In this talk, I will first describe a loop-less version of the Sagnac interferometer and microscope that has achieved unprecedented nanoradian level Kerr and Faraday sensitivity even at DC. With this Sagnac technique, I will discuss a few examples of our Sagnac studies of 2D magnetism and superconductivity. In exfoliated Cr2Ge2Te6 (CGT), we report [2] the discovery of intrinsic ferromagnetism in 2D van der Walls crystals, defying the well-known Mermin-Wagner theorem. In epitaxial Bi/Ni bilayer samples, we report [3] the observation of 2D superconductivity that spontaneously breaks TRS, which might have an order parameter with a nonzero phase winding number around the Fermi surface, making it a rare example of a 2D topological superconductor. In the Fe-Chalcogenide superconductor FeTe1−xSex, we found intertwined magnetism and superconductivity in its topological surface state [4]. Additionally, our study on exfoliated FeTe1−xSex flakes indicates the existence of a chiral edge state that may be useful for robust quantum computing (unpublished).

1. “The Effect of the Earth’s Rotation on the Velocity of Light, II” Michelson, A. A.; Gale, Henry G. (1925). Astrophysical Journal. 61: 140.
2. “Discovery of intrinsic ferromagnetism in 2D van der Waals crystals”, Nature, 546, 265-269 (2017).
3. “Time-Reversal-Symmetry-Breaking Superconductivity in Epitaxial Bismuth/Nickel Bilayers”, Science Advances, 3, 3, e1602579 (2017).
4. “Revealing the Origin of Time-Reversal Symmetry Breaking in Fe-Chalcogenide Superconductor FeTe1−xSex”. Physical Review Letters, 130(4):046702 (2023)

The complex interplay between the quantum degrees of freedom in oxides is known to cause a rich variety of intriguing emergent phenomena. While model Hamiltonians are often used to capture the underlying physics, they could be difficult to solve theoretically. This challenge calls for model-based designs for materials synthesis and measurement controls to experimentally simulate the corresponding behaviors. In this talk, I will review examples from our recent work that exploited this strategy to investigate the correlation-topology interplay in the Hubbard Hamiltonian, metallization of the dipolar spin ice Hamiltonian, and competition between orthogonal magnetic anisotropy. The results showcase the use of symmetry as the guide to implement the key ingredients of the targeted model in the experiment designs, which synergistically combine atomic layering synthesis, single-crystal growth, ultralow-temperature high-field transport measurements, and/or synchrotron x-ray scattering with multi-modal controls. New opportunities enabled by most recent capability advances will be discussed as well.

Over the last century, the construction and discovery of the Standard Model of particle physics has been one of the greatest accomplishments in physics. To explore this new frontier, we built larger and larger colliders utilizing the two charged particles that are easiest to produce and manipulate, the proton and the electron. As we contemplate the future of high energy colliders, the use of these particles fundamentally limits our potential energy reach: the low electron mass due to synchrotron radiation and the proton due to its composite nature. Luckily, the Standard Model provides an alternative: the muon. In this talk, I’ll discuss the challenges and possibilities of a muon collider, and give an overview of recent progress towards making one a reality.

The annual Honors Day celebration will be in Room 272C/Ballroom C at the Student Union.
We look forward to celebrating our staff for their extraordinary service and our students for their academic, leadership, and research achievements. The Society of Physics Students and Graduate Physics Society will also honor outstanding faculty members for exemplary teaching and advising.

The event begins at 3:30 pm.

Questions that drive searches for physics beyond the Standard Model include the physical origin of the cosmic baryon asymmetry and of dark matter. Quark dynamics, as realized through the theory of quantum chromodynamics (QCD), can appear in these studies in very different ways. In this talk, I develop these possibilities explicitly, first describing the role of QCD in ultra-sensitive searches for new physics, particularly at low energies, and then turning to how its features could be exploited in describing the undiscovered universe, along with the essential observational and experimental tests that could confirm them.

The strongest fundamental force of nature generates ~96% of the mass of the visible universe and binds together the building blocks of quantum chromodynamics, quarks and gluons, within the proton. At temperatures of a few trillion Kelvin or densities tens of trillions times more dense than iron, these quarks are no longer bound within protons and can form entirely new states of matter. It is possible to unlock these quark phases in heavy-ion collisions that reach the hottest temperatures on Earth or potentially in the core of neutron stars that have densities many times larger than that of a nucleus. In this talk, we will explore different ways to study the phases of matter of quarks from the lab using heavy-ion collision and in the cosmos using X-Ray measurements of neutron stars or gravitational waves from binary neutron star mergers.

Co-presented with Adrian Del Maestro (Physics/EECS), Kate Page (MSE), Claudia Rawn (MSE), and Corey Hodge (UT MRSEC)

The University of Tennessee has recently been awarded a prestigious Materials Research Science and Engineering Center by the National Science Foundation. The Center for Advanced Materials and Manufacturing is hosted at IAMM HQ, Knoxville as well as the Shull Wollan Center on the ORNL Campus. This Center builds on longstanding partnerships with ORNL in advanced computing, neutron science, and materials. The MRSEC involves more than 80 faculty, postdocs, and students and joins the network of MRSECs nationwide in offering unique capabilities to the national science community. This talk will present the center, its research, education, and outreach activities as well as its connections with the facilities and ways to get involved.

The formulation of quantum mechanics in the late 1920s forever changed physics. More recently, quantum materials have emerged, offering fascinating opportunities in condensed matter physics. Elementary interactions among elements such as electrons, phonons, and other quasiparticles in quantum materials give rise to the emergence of intriguing phases and offer enormous opportunities for the development of quantum technologies. But investigating these interactions at the relevant length scale requires high-resolution methods. Traditional far-field optical imaging and spectroscopy techniques are constrained by the diffraction limit of light. Interestingly, during the same period in the late 1920s, a visionary scientist named Synge introduced a groundbreaking concept that could circumvent the diffraction limit. Synge shared his idea with Einstein, who encouraged him to publish it. After many years of various pioneering works by different groups, a powerful modern nano-optical technique, a variant of Synge’s original idea, was born. In this talk, I will introduce this technique and give examples of high-resolution probing of nanoscale physical phenomena and interactions in two classes of quantum materials: correlated oxides and van der Waals (vdW) crystals. Our recent results reveal how an applied field perturbs dopant distribution at the nanoscale in correlated oxides such as rare-earth nickelates (RNiO3 where R = rare-earth element), leading to ordered reconfigurable phases. This reconfigurability enables the design of robust artificial synapses and opens new frontiers for fundamental understanding of memory, learning, and information retention for brain-inspired information processing. Correlated oxides also provide exciting opportunities to reconfigure polaritons, hybrid light-matter modes, in vdW crystals at the nanoscale, due to their highly tunable local optical and electronic properties. I will introduce a hybrid polaritonic-oxide heterostructure platform consisting of vdW crystals, such as hexagonal boron nitride or alpha-phase molybdenum trioxide, transferred on nanoscale oxygen vacancy patterns on the surface of correlated perovskite oxides. Hydrogenation and temperature modulation allow spatially localized conductivity modulation of the oxide nanoscale patterns, enabling robust real-time modulation and nanoscale reconfiguration of hyperbolic polaritons

Excitons are quasiparticles that emerge when a valence electron is promoted in energy to the conduction states, leaving behind a hole that interacts with the electron. Many aspects of exciton physics in traditional insulators are well understood. However, in correlated quantum materials, the situation becomes richer and more complex due to the emergence of many-body excitons, which involve strong electron-electron and electron-spin interactions. In this talk I will explain the technique of resonant inelastic x-ray scattering [1], which we have recently been applying to several aspects of exciton physics. This includes the identification of an antiferromagnetic excitonic insulator state in Sr3Ir2O7 [2], determining the nature of propagating magnetically propagating Hund’s excitons in NiPS3 [3], and the Floquet renormalization of the charge-transfer exciton in La2-xSrxCuO4.

[1] Exploring Quantum Materials with Resonant Inelastic X-Ray Scattering, M. Mitrano, S. Johnston, Young-June Kim, and M. P. M. Dean, submitted (2024)

[2] Antiferromagnetic excitonic insulator state in Sr3Ir2O7, D. G. Mazzone et al., Nature Communications 13, 913 (2022)

[3] Magnetically propagating Hund’s exciton in van der Waals antiferromagnet NiPS3, W. He et al., in press at Nature Communications (2024)

Understanding the origin of life on Earth motivates many of the questions that drive inquiry across all scientific subfields. Certainly, such questions influence nuclear and particle physics research. For example, the matter-antimatter asymmetry observed in today’s Universe is necessary for our existence, but its origin in not well understood. The neutrino may play a significant role in understanding this asymmetry. Specifically, a promising class of theories that explains the asymmetry requires that the neutrino be its own anti-particle. The nuclear process of neutrinoless double-beta decay (0νΒΒ) can only occur if neutrinos have mass and are their own antiparticle. Although it is known that neutrinos have a small mass, we do not know the value or their particle-antiparticle nature. If a rate for 0νΒΒ is measured it will help elucidate the mass, but critically, 0νΒΒ is the only feasible experimental technique to determine if light neutrinos are their own antiparticle. This situation has resulted in a great deal of excitement for 0νΒΒ research.

This Colloquium will discuss the motivations for the search for 0νΒΒ, the experimental issues, and the use of the radiation-detection technology of germanium detectors to search for this process; the Majorana and LEGEND experiments.

A quantum spin liquid (QSL) arises from a highly entangled superposition of many degenerate classical ground states in a frustrated magnet, and is characterized by emergent gauge fields and deconfined fractionalized excitations (spinons). Because such a novel phase of matter is relevant to high-transition-temperature superconductivity and quantum computation, the microscopic understanding of QSL states is a long-sought goal in condensed matter physics. Although Kitaev QSL exists in an exactly solvable spin-1/2 (S=1/2) model on a two-dimensional (2D) honeycomb lattice, there is currently no conclusive identification of a Kitaev QSL material. The 3D pyrochlore lattice of corner-sharing tetrahedra, on the other hand, can host a QSL with U(1) gauge fields called quantum spin ice (QSI), which is a quantum (with effective S=1/2) analog of the classical (with large effective moment) spin ice. The key difference between a QSI and classical spin ice is the predicted presence of the linearly dispersing collective excitations near zero energy, dubbed the “photons” arising from emergent quantum electrodynamics, in addition to the spinons at higher energies. Recently, 3D pyrochlore systems Ce2M2O7 (M = Sn, Zr, Hf) have been suggested as effective S=1/2 QSI candidates, but there has been no evidence of quasielastic magnetic scattering signals from photons, a key signature for a QSI. Here, we use polarized neutron scattering experiments on single crystals of Ce2Zr2O7 to conclusively demonstrate the presence of magnetic excitations near zero energy at 50 mK in addition to the signatures of spinons at higher energies. By comparing the energy (E), wave vector (Q), and polarization dependence of the magnetic excitations with theoretical calculations, we conclude that Ce2Zr2O7 is the first example of a dipolar-octupolar π-flux QSI with dominant dipolar Ising interactions, therefore identifying a microscopic Hamiltonian responsible for a QSL.

This colloquium introduces the underlying theory and computational algorithms used to simulate the low-energy interactions of protons and neutrons using a three-dimensional lattice grid. Some of the topics to be discussed are nuclear clustering, intrinsic shapes, nuclear binding energies and charge radii, the nuclear equation of state, the liquid-vapor transition in nuclear matter, and superfluidity.

A free neutron provides the simplest example of nuclear $\beta$-decay, leading to a unique suite of tests for fundamental parameters of electroweak theory and the Standard Model of particle physics. A free neutron decays into a proton, electron, and antineutrino. This decay can be used to extract the CKM quark-mixing matrix element $V_{ud}$ without the need for nuclear structure corrections, which could resolve present tensions or hunt for new physics. This extraction requires two measurements: the neutron lifetime, $\tau_n$; and the relative coupling strength of the Vector and Axial-Vector currents in the weak interaction, $\lambda$. This talk will provide an overview of this decay process, beginning with measurements of the neutron lifetime. Then, this talk will focus on measuring $\lambda$, presenting an early look at results from the Nab experiment presently commissioning at Oak Ridge National Laboratory.

Over recent decades, the study of strongly correlated quantum materials, in which strong interactions between particles push the system into the non-perturbative regime, has revealed a plethora of new quantum states, each with unique physical properties beyond the reach of perturbation theory. A key hurdle in this arena is the non-perturbative nature of these states, making theoretical description and prediction of them a significant challenge. This talk aims to shed light on how flat band systems provide a distinctive platform for various nontrivial correlated phenomena to emerge as exact solutions in theoretical analysis. This facilitates reliable prediction and robust guidance to identify novel quantum states of matter. Examples such as non-Fermi liquids and the fractional quantum anomalous Hall effect will be illuminated, along with a discussion on yet-to-be-observed quantum states that might emerge in flat band systems, such as fractional quantum anomalous Hall smectic states.

There are many open questions in nuclear physics which only lattice QCD may be able to answer. One example is understanding the nature and origin of the fine-tuning of interactions between nucleons and nuclei observed in nature. The first step toward building a bridge between the underlying theory, QCD, and nuclear observables is full control over one- and two-nucleon systems. While enormous strides have been made in recent years in precision calculations of single-nucleon observables, the history of two-nucleon calculations has generated more questions than answers. In particular, there is a controversy in the literature between calculations performed using different theoretical techniques, even for calculations far from the physical point, chosen due to the exponentially simpler computational properties. In this talk, I will present the history and challenges behind one- and two-nucleon calculations in lattice QCD, as well as advances in understanding and controlling the associated systematics.

Neuromorphic computing is a popular technology for the future of computing. Much of the focus in neuromorphic computing research and development has focused on new architectures, devices, and materials, rather than in the software, algorithms, and applications of these systems. In this talk, I will overview the field of neuromorphic from the computer science perspective. I will give an introduction to spiking neural networks, as well as some of the most common algorithms used in the field. Finally, I will discuss the potential for using neuromorphic systems in real-world applications from scientific data analysis to autonomous vehicles.

Protein crystallography is an established technique for determining the structure and function of many protein systems. These measurements are essential for drug design, enzymology, and more. Light sources dominate this field due to their extremely high brightness, but neutrons have unique advantages such as sensitivity to light nuclei and isotopes. At ORNL, Dynamic Nuclear Polarization (DNP) is being used to take advantage of the nuclear spin dependence of neutron scattering and leverage that to overcome the large brightness disadvantage of neutron sources. The DNP technique will be described, as will test results, and the design and operation of a DNP enhanced IMAGINE instrument which will soon be installed at the High Flux Isotope Reactor (HFIR).

For more than 15 years, NANOGrav and other pulsar-timing array collaborations have been carefully monitoring networks of pulsars across the Milky Way. The goal was to find a tell-tale correlation signature amid the data from all those pulsars that would signal the presence of an all-sky background of nanohertz-frequency gravitational waves, washing through the Galaxy. At the end of June this year, NANOGrav finally announced its evidence for this gravitational-wave background, along with a series of studies that interpreted this signal as either originating from a population of supermassive black-hole binary systems, or as relics from cosmological processes in the very early Universe. I will describe NANOGrav’s journey up to this point, what led to the ultimate breakthrough, how this affects our knowledge of supermassive black holes and the early Universe, and what lies next for gravitational-wave astronomy at nanohertz frequencies.

The strong force in nature, which is at the core of nuclear-physics phenomena, is described by the theory of quantum chromodynamics (QCD). It has long generated an active and growing field of research and discovery. In fact, despite the development of QCD more than half a century ago, plenty of questions remain open into the 21st century: What does the phase diagram of matter governed by strong interactions, such as the interior of neutron stars, look like? How does matter evolve and thermalize after energetic processes such as after the Big Bang or in particle colliders? How do elementary particles in QCD and their interactions give rise to the complex structure of a proton or a nucleus, and their response to various probes? A successful program called lattice QCD has enabled a first-principles look into some properties of matter with the aid of classical computing. At the same time, we have yet to come up with a more powerful computational tool to predict the complex dynamics of matter from the underlying interactions. Can a large reliable (digital or analog) quantum simulator eventually enable studies of the strong force? What does a quantum simulator have to offer to simulate QCD, and how far away are we from such a dream? In this talk, I will describe a vision for how we may go on a journey toward quantum simulating QCD, by taking insights from early to late developments of lattice QCD and its achievements, by motivating the need for novel theoretical, algorithmic, and hardware approaches to quantum-simulating this unique problem, and by providing examples of the early steps taken to date in establishing a quantum-computational lattice-QCD program.

A recurring theme in condensed-matter physics has been the discovery and exploration of macroscopic quantum phenomena as consequences of strong electron-electron interactions, such as magnetism, superconductivity, and fractionalization. Bilayer graphene with a magic-angle artificial twist exemplifies a new paradigm of strongly interacting electrons, as witnessed in the past five years. In fact, naturally occurring rhombohedral graphene multi-layers are also fertile ground for strongly interacting electron physics. In this talk, I will first discuss their theory-oriented spontaneous chiral symmetry breaking, topological orbital magnetization, and quantum anomalous Hall effect at charge neutrality, which have all been observed in experiment. Then I will introduce their experiment-oriented ferromagnetism, superconductivity, electron crystallization, and fractional quantum anomalous Hall effect under ultra-low doping. If time permits, I will show how SU(3) flavor physics analogous to the quark model can also emerge in this system.

Atomic nuclei exhibit multiple energy scales ranging from hundreds of MeV in binding energies to fractions of an MeV for low-lying collective excitations. Describing these different energy scales within an ab-initio framework is a long-standing challenge. In this talk I will show how we overcome this challenge by using high-performance computing, many-body methods with polynomial scaling, and ideas from effective-field-theory. This progress enables us to address fundamental questions related to the how nucleons organize themselves in shell away from the valley of beta-stability, nuclear deformation and the limits of the nuclear chart, the role of meson-exchange currents and strong correlations in Gamow-Teller transitions, and the nature of the neutrino from computations of neutrino-less double beta decay and lepton-nucleus scattering on relevant nuclei. New ways to make quantified predictions are now possible by the development of accurate emulators of ab-initio calculations. These emulators reduce the computational cost by many orders of magnitude. This allows us to perform global sensitivity analysis, and use novel statistical tools to make quantified predictions for the neutron skin in 208Pb, the binding energy of exotic 28O, and what drives deformation in neon and magnesium isotopes. With this talk I hope to convey that the accurate computation of multiscale nuclear physics demonstrates the predictive power of modern ab initio methods.

Sixty plus years ago parity violation by the weak force was demonstrated in experiments led by Chien-Shiung Wu on the asymmetry of electron currents emitted in the beta decay of polarized 60Co. The asymmetry reflects two broken symmetries – mirror reflection and time-reversal, the latter imposed by an external magnetic field. The same year Bardeen, Cooper and Schrieffer published the celebrated BCS theory of superconductivity, and soon thereafter P. W. Anderson and P. Morel proposed that the ground-state of liquid 3He (the light isotope of Helium) was possibly a BCS superfluid exhibiting spontaneously broken mirror reflection and time-reversal symmetries. Indeed superfluid 3He-A, discovered in 1972, is the realization of a quantum state of matter that violates both parity and time-reversal symmetry. Definitive proof of broken mirror symmetry in 3He-A came 41 years later from the observation of asymmetry in the motion of electrons in superfluid 3He-A.1 I discuss these and related discoveries, as well as the physics underlying anomalous electron transport in such quantum systems with broken mirror and time-reversal symmetries.2,3

H. Ikegami, Y. Tsutsumi, & K. Kono, Chiral Symmetry in Superfluid 3He-A, Science, 341,59–62, 2013.
O. Shevtsov & J. A. Sauls, Electrons & Weyl Fermions in Superfluid 3He-A, Phys. Rev. B, 94, 064511, 2016.
V. Ngampruetikorn & J. A. Sauls, Anomalous Thermal Hall Effect in Chiral Superconductors, PRL 124, 157002 (2020).
† Research supported by NSF grant DMR-1508730.

The Large Hadron Collider at CERN is a two-beam proton synchrotron with a design energy per proton beam of 7 Tera-electron volts. It has been operating at CERN since 2010, with the high-profile success of finding the Higgs boson in 2012, thus completing the standard model of particle physics. The collider has been running since, and now preparations are being made to upgrade the collision rate (luminosity) of the proton collisions through the HL-LHC project. This upgrade will permit high precision measurements and more sensitive particle searches and involves considerable accelerator upgrade. This talk will review the LHC accelerator, the luminosity upgrade and present some of the UK’s contributions to this project. Following this, several public engagement projects linked to the LHC are presented, which attempt to communicate the science of the LHC to a range of diverse audiences, using a range of diverse methods.

Previous measurements of the anomalous magnetic moment of the muon have shown a sizeable discrepancy with standard model calculations, which might be indicative of new physics. We present a new measurement from the Fermilab Muon g-2 experiment with twice the precision of our prior result.

Plato is quoted as saying “If you do not take an interest in the affairs of your government, then you are doomed to live under the rule of fools.” Scientists have long been underrepresented in seats of political power. The 117th Congress had only one physicist, one chemist, and one geologist. In my talk I will discuss what it is like transitioning from being a scientist managing maintenance on the Spallation Neutron Source at the Oak Ridge National Laboratory to a career in local and state politics, and how my scientific training has aided my decision making.

Particle interactions create static and dynamic correlations even in seemingly disordered systems, and such correlations determine the properties, for instance through the fluctuation-dissipation theorem. Thus, figuring out such correlations is the key to understanding dynamic aperiodic matter (DAM), such as liquid, glass and itinerant electrons (Fermi liquid). However, correlations are often concealed and hard to detect by experiments, making the studies difficult, but interesting. I discuss two recent breakthrough examples by my research group, one on the glass transition and the other on the high-temperature superconductivity (HTSC). These two appear totally disconnected, but actually similar experimental approaches to dynamic correlation, the dynamic pair-distribution function determined by neutron/x-ray scattering or by simulation, brought us to the goal. In the case of the glass transition the discovery of density wave instability in liquid was the key [1], and for the HTSC the crucial step was the recognition that the electron dynamics affects electron correlation and the Bose-Einstein condensation [2].

1. T. Egami and C. W. Ryu, Frontiers in Materials, 9, 874191 (2022); J. Phys: Condens. Matter, 35, 174002 (2023).
2. T. Egami, Physica C, 613, 1354345 (2023).

In the simplest electroweak nuclear reaction, the proton-proton fusion process, two protons combine into a deuteron while emitting a positron and a neutrino. It is the starting point of the chain of fusion reactions that generate the sun’s energy. Only effective field theory can provide a high precision, first principles description of this process needed for modern stellar models. Such a calculation requires not only the nuclear interaction but also electroweak one- and two-body currents derived in a consistent effective field theory framework. I will review the effective field formalisms used to describe this process. I will explain how it depends on fundamental electroweak two-nucleon properties, and how these can be measured in complementary experiments. I will also discuss how the same tools as in proton-proton fusion can be used to describe electroweak processes involving so-called halo nuclei consisting of a tightly bound core and weakly bound valence nucleons.

The continuing development of production and separation techniques allowing for the study of nuclei far away from the line of stability has spurred the low energy nuclear field for the past three decades. Large proton-neutron imbalances drive emerging exotic phenomena such as shape coexistence or halo distributions of nuclear matter, which in turn have helped refine our understanding of the nuclear interaction in the nuclear medium. In this talk I will discuss our experimental efforts using beta-delayed gamma and neutron spectroscopy to characterize the nuclear structure of neutron rich nuclei around doubly magic 132Sn. In particular I will concentrate in the role nucleon excitations across shell closures play in all three regions, driving both increasingly smaller decay-half lives and larger neutron branching ratios.

The Quantum Science Center is a National Quantum Information Science Research Center headquartered at Oak Ridge National Laboratory. The purpose of the center is to discover and innovate in the field of quantum information science (QIS) to ensure American scientific leadership, economic competitiveness, and national security. QSC addresses this mandate by targeting three major scientific challenges 1) quantum simulation platforms for scientific discovery applications, 2) quantum sensing for real-world applications, and 3) topological quantum materials for new quantum devices. This talk will give an overview of the center’s scientific goals as well as highlights of recent scientific impacts and their outcomes in each of these areas.

Join us as we honor outstanding students, faculty, and staff at the annual UT Physics Honors Day celebration.

The merging of two neutron stars is a true multimessenger event that includes gravitational waves, an electromagnetic signal, and the emission of enormous numbers of neutrinos. In order to understand these signals we need a careful accounting of the microphysics that occurs during and after the merger. I will focus on the elements produced in these objects and the effect of two aspects of this microphysics; nuclear models/reactions and neutrino flavor transformation physics. In particular, I will discuss the importance of new developments in these areas to predictions of r-process observables and the astrophysical origin of the r-process.

The CERN Large Hadron Collider (LHC) has discovered the Higgs boson and confirmed the predictions for many of its properties given by the “Standard Model” of particle physics. However, this does not mean that particle physics is solved. Mysteries that the Standard Model does not address are still with us and, indeed, stand out more sharply than ever. To understand these mysteries, we need experiments at still higher energies. In this colloquium, I will argue that we should be planning for a particle collider reaching energies of about 10 times those of the LHC in the collisions of elementary particles. Today, there is no technology that can produce such energies robustly and at a reasonable cost. However, many solutions are under study, including colliders for protons, muons, electrons, and photons. I will review the status of these approaches to the design of the next great energy-frontier accelerator.

Majorana zero modes are fermion-like excitations that were originally proposed in particle physics by Ettore Majorana and are characterized as being their own anti-particle. In condensed matter systems, Majorana zero modes occur as fractionalized excitations with topologically protected degeneracy associated with such excitations. For over a decade, the only candidate systems for observing Majorana zero modes were the non-Abelian fractional quantum Hall state and chiral p-wave superconductors. In this colloquium, I will start by explaining the basic ideas of topological quantum computation using Majorana zero modes. This will be followed by a status update on transport experiments on potential Majorana systems including the recent experiments on Microsoft as well as those in iron superconductors. I will then provide a more detailed explanation of braiding, Majorana operators, and the associated topological degeneracy. I will end with my outlook on the challenges and future directions.

Long-baseline neutrino oscillation experiments present some of the most compelling paths towards beyond-the-standard-model physics through measurement of PMNS matrix elements and observation of the degree of leptonic CP violation. State-of-the-art long-baseline oscillation experiments, like NOvA and T2K, are currently statistically limited, however uncertainty in neutrino-nucleus scattering represents an important source of systematic uncertainty in future experiments like DUNE and Hyper-Kamiokande. Neutrino cross-section uncertainties can be reduced through high-statistics measurement of neutrino interactions on light nuclei, but creating a detector with an appropriate light target has proved elusive since the hydrogen bubble chambers designed in the 70’s. Modern bubble chamber-based dark matter detectors like PICO and the Scintillating Bubble Chamber have demonstrated that advances in sensor technology, computing, and automation would allow a modern bubble chamber to fully utilize the megawatt scale intensity LBNF beam. This talk will review the broad physics program and the construction of a hydrogen bubble chamber for use with neutrinos at Fermilab.

This talk discusses two examples of how a combination of analytical and computational methods can serve to connect basic theoretical ideas about correlated states to quantum information quantities and neutron scattering experiments. The ground state of a chain of antiferromagnetically interacting spins (the 1D “Heisenberg model”) is one of the solvable hydrogen atoms of many-body physics, but its dynamics remained opaque for eighty years. We introduce the Heisenberg model’s novel fluid-like dynamical regime at high temperatures and describe its realization in a variety of recent experiments ranging from neutron scattering on crystals to optical lattice emulation with atoms. It turns out that the dynamics of spins in this canonical model are described by the Kardar-Parisi-Zhang dynamical universality class, which is well known from classical problems such as driven interfaces. For frustrated systems in higher dimensions, controlled comparisons between theory and experiment are more difficult except for a small number of tractable cases. We forge ahead nevertheless and present theoretical arguments that a chiral spin liquid is likely to appear near the Mott transition in some triangular lattice materials, and second, that other kinds of spin liquids and quantum critical points are suggested in recent experiments.

In my talk, I review recent and not so recent works aiming to understand whether a nominally repulsive Coulomb interaction can give rise to superconductivity. I discuss a generic scenario of the pairing, put forward by Kohn and Luttinger back in 1965, and briefly review modern studies of the electronic mechanisms of superconductivity in the lattice systems, which model cuprates, Fe-based superconductors, and even doped graphene. I show that the pairing in all three classes of materials can be viewed as a lattice version of Kohn-Luttinger physics, despite that the pairing symmetries are different. I discuss under what condition the pairing occurs and rationalize the need to do renormalization-group studies. I also discuss most recent work on the pairing near a quantum-critical point, particularly the interplay between superconductivity and non-Fermi liquid physics.

Quantum materials provide responses and states of matter with no classical analogues. As such they offer opportunities to create an array of platforms for future devices crucial to human health, energy efficiency, communications and imaging. I will begin by describing the physics challenges and sensing opportunities these materials offer. I will then focus on our use of the relativistic electrons in graphene for biosensing. Specifically we have developed a new platform for multiplexed, rapid, easy to use detectors of biological analytes. I will discuss the unique aspects of graphene involved resulting in our demonstration of the detection of antibiotic resistant bacteria, decease biomarkers in saliva, opioids in waste water and respiratory infection at clinically relevant levels. Time permitting I will explain our efforts to use quantum materials to create new quantum simulators.

Neutron star mergers are connected to some of the most pressing open questions in physics and astrophysics, ranging from the nature of strong gravity, to the behavior of QCD in the non-perturbative regime, to the origin of the heavy elements. Multimessenger observations of these events hold the key to unlock these mysteries. However, theory is needed to turn data into answers. In this talk, I will discuss our efforts to model binary neutron star mergers in numerical relativity. I will talk about new developments in the simulation technology and I will present some recent results. Finally, I will talk about challenges and prospectives in this field.

Although Dark Matter (DM) comprises most of the mass of the Universe, the physical nature of DM remains unknown. The hypothesis that DM made of heavy Super Symmetric particles was refuted by LHC. Very light DM candidates axion cannot be found after several decades of searches. Direct searches for DM lack any signal of heavy and light DM particles. We will discuss a model where dark matter particles are a twin-copy of our ordinary particles with the same masses, charges, spins, interactions, thus forming similar atoms, molecules, planets, stars, etc. These DM particles are separated from us by small extra dimension, which makes them invisible for us but does not exclude their gravitational interaction with ordinary matter and between themselves. Such a model of Dark Matter was named a Mirror Matter model. Neutral particles in the ordinary and mirror worlds can be mixed with each other via extra dimensional tunneling and form, in this way, an “interaction portal” between two worlds. Thus, the neutron of our world (n) can be mixed with the mirror neutron (n’) leading to quantum-mechanical transformations n -> n’ and n’ -> n, the process called oscillations. Interaction of neutron components with the environment in both worlds (magnetic field, matter gas) might lead to the observable and reproducible effects that we will addressed in this talk. Some controversial observations pointing to the possible presence of the mirror neutron effects and results of the first searches for “mirror neutrons” will be discussed.

Detection of ultrahigh energy (UHE) neutrinos is key to identifying the most energetic objects and processes in the universe. These are the sources of UHE cosmic rays, which have been detected at earth with energies exceeding 1 Joule per nucleon (roughly the kinetic energy of a bird in flight). As UHE cosmic messengers, neutrinos are unparalleled for their ability to travel from source to Earth, interacting only weakly with matter and therefore able to traverse great distances unimpeded. For this same reason, however, they are very difficult to detect (and additionally at high energies, a vanishingly small number arrive at earth).

In this talk, I will discuss the general challenges in detecting UHE neutrinos, and the extensive experimental work that has been done so far to meet these challenges using various detection strategies. I’ll focus on a forthcoming experimental effort, the Radar Echo Telescope (RET), which uses well-known radar technology to attempt detection of the cascade produced by these elusive neutrinos as they interact in polar ice. I’ll discuss the theory and storied history of astroparticle physics, the radar echo method, recent laboratory work, and our current experimental efforts in service of UHE neutrino detection with RET.

Using circularly-polarized light to control quantum matter is a highly intriguing topic in physics, chemistry and biology. Previous studies have demonstrated helicity-dependent optical control of spatial chirality and magnetization M. The former is central for asymmetric synthesis in chemistry and homochirality in bio-molecules, while the latter is of great interest for ferromagnetic spintronics. In this paper, the authors report the surprising observation of helicity-dependent optical control of fully-compensated antiferromagnetic (AFM) order in 2D even-layered MnBi2Te4, a topological Axion insulator with neither chirality nor M. They demonstrated helicity-dependent optical creation of AFM domain walls by double induction beams and the direct reversal of AFM domains by ultrafast pulses. The control and reversal of AFM domains and domain walls by light helicity have never been achieved in any fully-compensated AFM. To understand this optical control, the authors studied an AFM circular dichroism (CD) proportional to the AFM order, which only appears in reflection but is absent in transmission. They showed that the optical control and CD both arise from the optical Axion electrodynamics. The Axion induction provides the possibility to optically control a family of PT-symmetric AFMs such as Cr2O3, even-layered CrI3 and possibly pseudo-gap state in cuprates. In MnBi2Te4, this further opens the door for optical writing of dissipationless circuit formed by topological edge states.

Who Ordered That? I.I. Rabi asked this question when a new particle, the muon, was discovered in 1936. Ever since, this unexpected particle has constantly brought us more surprises, including the pion discovery, parity violation, J/psi discovery, neutrinos and flavor physics etc., opening an avenue in front of us to new physics and new technology. In this talk, I will discuss a new aspect — a high energy muon collider. Due to the recent technological breakthroughs for muon cooling, the muon collider program has regained its momentum. I will present the idea and the current status for a muon collider, and discuss the rich physics potential in exploring the physics beyond the Standard Model, for two representative scenarios: the Higgs factory for the resonant Higgs production and the multi-TeV muon collider at the energy frontier.