Dr. Kyle Leach

Associate Professor

Department of Physics

Colorado School of Mines

Host: Korsch

Title: Hunting for Ghosts using Rare-Isotope Doped Superconducting and Optomechanical Sensors

Abstract: Nuclear beta and electron capture (EC) decay serve as sensitive probes of the structure and symmetries at the microscopic scale of our Universe. As such, precision measurements of the final-state products in these processes can be used as powerful laboratories to search for new physics from the meV to TeV scale. Significant advances in “rare isotope” availability and quality, coupled with decades of sensing technique development from the AMO community have led us into a new era of fundamental tests of nature using unstable nuclei. For the past few years, we have taken the approach of embedding radioisotopes in thin-film superconducting tunnel junctions (STJs) to precisely measure the recoiling atom that gets an eV-scale “kick” from the neutrino following EC decay. These recoils are encoded with the fundamental quantum information of the neutrino and decay process, as well as carrying unique signatures of weakly coupled beyond standard model (BSM) physics; including neutrino mass, exotic weak currents, and potential “dark” particles created within the energy-window of the decay. These measurements provide a complimentary and (crucially) model-independent portal to the dark sector with sensitivities that push towards synergy between laboratory and cosmological probes. In this talk, I will discuss the broad program we have developed to provide leading limits in these areas as well as the technological advances across several sub-disciplines of science required to enable this work, including subatomic physics, quantum engineering, atomic theory, and materials science. Finally, I will discuss future prospects of extending this work using macroscopic amounts of harvested exotic atoms from the Facility for Rare Isotope Beams (FRIB) in optically levitated nanospheres for direct momentum measurements of the decay recoils.

Dr. Anushya Chandran

Associate Professor

Department of Physics

Boston University

Host: Murthy

Title: TBA

Abstract: TBA

Dr. Zein-Eddine Mezziani

Senior Physicist and Group Leader

Argonne National Laboratory

Host: Korsch

Title: TBA

Abstract: TBA

Rosi Reed

Associate Professor

Lehigh University

Department of Physics

Host: Renee Fatemi

Title: Golden Age of Jet Tomography in Heavy Ion Collisions: The Evolution of Jets as Probes of the Quark Gluon Plasma

Abstract: The strong nuclear force, or quantum chromodynamics (QCD), remains one of the most enigmatic of the four fundamental forces of nature due to its rich structure and many emergent properties. The collision of heavy ions at ultra-relativistic speeds gives rise to a remarkable medium known as the quark gluon plasma (QGP). In this extreme state of QCD matter, protons and neutrons dissolve into partons - quarks and gluons - creating a nearly perfect liquid.  A fundamental question is whether quasi-particles exist in this medium, given the incredibly low viscosity over entropy ratio.  Answering questions regarding the evolution of the QGP structure, and the connection to QCD, requires probes with extremely small spatial resolution. Enter the particle jets created in high momentum transfer parton-parton collisions. These jets, produced early in the heavy-ion collision evolution, traverse the newly formed QGP and lose energy in a process called jet quenching, which modifies the final state properties of the resultant jets.  Understanding the mechanisms of jet quenching will allow the determination of QGP transport coefficients and thus lead to a better understanding of QCD.  The path-length dependence of the jet energy loss is one way to better understand the underlying mechanisms, though it has proven challenging to derive explicit values for the path-length dependence from experimental data.  We can gain critical insights into the nature of the QGP at both the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), to determine the temperature dependence, and system-size dependence of many jet observables.  In this presentation, I will discuss the latest Solenoidal Tracker at RHIC (STAR) experimental jet results, including a new measurement of the azimuthal asymmetry of jets in Ruthenium and Zirconium collisions, and compare these results with similar results from the LHC experiments, as well as the potential outlook for measurements with the newly built sPHENIX detector.  I will compare these results to recent advances in theory and connect them to other heavy ion jet measurements such as photon jet correlations and measurements of the structure of the jets themselves.

Prof. Robert Stamps

Department of Physics and Astronomy

University of Manitoba

Host: Lance DeLong and Todd Hastings

Title: Spin Vision: Using Artificial Spin Ice to Study Complex Systems

Abstract: Artificial Spin Ice is the name given to a class of metamaterials that are used as models for frustrated systems. In these models, frustration is introduced through competing interactions in a mesoscopic-scale array of interacting particles. Their experimental realization using nanomagnets as the interacting particles was first demonstrated in 2006 and opened a new field of study for frustrated systems. [1] As models in experiment, Artificial Spin Ice facilitate detailed observation in real time with high spatial resolution of complex out of equilibrium dynamics and thermodynamic processes. This flexibility underwrites their use in fundamental studies of a variety of nonlinear dynamics and ordering phenomena in low dimensions. 

Recent advances in fabrication now enable creation of complex two- and three-dimensional structures that have opened new possibilities for structural design and exciting new potentials for application in practical devices. [2] In this talk, a new cross-discipline direction for research that can benefit from Artificial Spin Ice models is explored. Motivated by studies of neural network models used in the analysis of experiments on primate vision, [3,4] a new type of three-dimensional Artificial Spin Ice geometry is proposed for implementation of a biologically plausible neuroscientific model called ‘active inference’. [5] Cast in the form of nanomagnetic spin geometries that can be studied experimentally, the approach can be used to facilitate a physics-based understanding of how complex systems might spontaneously generate a type of Bayesian filtering.

To achieve this, novel mechanisms for the control of magnetic states and ordering processes using three-dimensional geometries are required and different strategies are discussed. [6,7] A rudimentary ‘smart ASI’ is described whose design is based on state optimization principles assumed in some models used to describe general neurological processes.

1. RF Wang et al., Nature 439, 303 (2006).
2. SH Skjærvø, CH Marrows, RL Stamps, LJ Heyderman, Nature Reviews Physics 2, 13 (2020).
3. M Falconbridge, RL Stamps, DR Badcock, Neural Computation 18, 415 (2006).
4. M Falconbridge, RL Stamps, M Edwards, DR Badcock, i-Perception (in press).
5. RA Adams, E Aponte, L Marshall, KJ Friston, J. Neuroscience Methods 242, 1 (2015).
6. VM Parakkat, GM Macauley, RL Stamps, KM Krishnan, Physical Review Letters 126, 017203 (2021).
7. RB Popy, J Frank, RL Stamps, Journal of Applied Physics 132, 133902 (2022).

Tracy Webb

Associate Professor

Department of Physics

McGill University

Host: Yuanyuan Su

Title: Witnessing the evolution of the most massive galaxies in the densest regions of the universe

Abstract: An understanding of the formation and evolution of massive galaxies is a forefront goal of astrophysics today, observationally and theoretically. While we generally understand structure growth in the context of CDM hierarchical structure formation, and indeed this idea has been highly successful, new observations have shown that baryonic physics plays a key role. Indeed, the complex physics of galaxy-galaxy mergers, large scale gas cooling, and AGN feeding and feedback drive the evolution of massive galaxies. Given that at any given cosmic epoch the most massive galaxies tend to be found in over dense regions of the universe, one way to observationally find and study these systems is through a search for such peaks. In this talk I will describe, after introducing the field, an ongoing observational program to understand the evolutionary growth of massive galaxies that sit at the centres of giant galaxy clusters. With a focus on key systems and multiwaveIength data, I will argue that we do not yet fully understand how these giant beasts build up their stellar mass, but that progress is being made through efforts to push our observations to earlier epochs with new tools. 

Jeyhan Kartaltepe

Associate Professor

School of Physics and Astronomy

Rochester Institute of Technology

Host: Ryan Sanders

Title: TBA

Abstract: TBA

Prof. Jeanie Lau

Department of Physics

The Ohio State University

Host: Chunli Huang

Title: Flat Bands and Quantum Geometry in Flatlands

Abstract: In a flat band, the electronic interactions dominate, leading to emergent correlated phases such as superconductivity and charge density waves. The advent of flatlands, i.e. two-dimensional (2D) materials provide us with unprecedented opportunities to design and engineer flat bands via stacking, magnetic fields, and twisting. For flat bands in flatlands, quantum geometric contributions become important. To illustrate this, I will focus on superconductivity in twisted bilayer graphene, in which the slow Fermi velocity and the small charge density appear to invalidate conventional BCS equations and present a paradox. The paradox is resolved by our experimental demonstration that the superfluid stiffness is dominated by the quantum geometric contribution. We also find that the band velocity in this Dirac superconductor constitutes a new limiting mechanism for the critical current, analogous to a relativistic superfluid. Finally, I will also present on flat bands in suspended few-layer graphene, where gate tunable magnetism is observed. 

Nathaniel Craig

Associate Professor

Department of Physics

University of California, Santa Barbara

Host: Susan Gardner

Title: The “Who Ordered That” Collider

Abstract: In this talk, I’ll survey some of the major open questions in particle physics and make the case that they can best be addressed by a qualitatively new type of particle accelerator: a high-energy muon collider.  Recent progress on long-standing accelerator and detector challenges make such a collider a compelling successor to the LHC.

Prof. Martin Kruczenski

Department of Physics and Astronomy

Purdue University

Host: Anatoly Dymarsky

Title: Two applications of positivity to the theory of strong interactions (QCD)

Abstract: Although the fundamental description of the strong interactions is known, at low energy the theory is strongly coupled and calculations are more difficult as happens in many other areas of physics where perturbation theory does not apply.  On the other hand, recently, positivity conditions have been used to improve and obtain new non-perturbative results in quantum field theory, matrix models, and even classical mechanics.  Motivated by these, I will discuss how to use positivity in the context of gauge theories to find a gauge invariant formulation of lattice gauge theories in terms of Wilson loops, to compute certain low energy scattering amplitudes in two and four dimensions and even to find orbits in classical systems. I will also briefly discuss how these new applications have been fueled by new optimization algorithms developed for similar problems in engineering and finance.