2025 Open House Poster Presentation Abstracts
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Sinho Chewi Group
Eric Regis, Graduate Student
eric.regis@yale.edu
Physics-Inspired Sampling
Sampling is the process of "drawing" from complex probability distributions. While recent advances in machine learning have brought renewed attention to physics-based techniques, the interplay between physics and sampling has deep roots, dating back to pioneering experiments by physicists at Los Alamos in the 40s and 50s.
This poster presents an overview of key physics-inspired sampling algorithms. We trace the development of physics-inspired sampling algorithms from Metropolis-Hastings to Langevin Monte Carlo to more modern approaches like diffusion models. We explore how these methods leverage physical principles to efficiently sample from high-dimensional and multi-modal probability distributions.
Eduardo H. da Silva Neto Group
Aaron G. Greenberg, Graduate Student
a.greenberg@yale.edu
Investigating Strong Electron-Electron Interactions in Kagome Superconductor CsV3Sb5
The nature of superconductivity in kagome metal CsV3Sb5 has long been debated, with
multiple studies providing evidence both for and against unconventional superconductivity[1]. To work towards finding a definitive answer, we present scanning tunneling spectroscopy (STS) measurements of CsV3Sb5 with high energy and momentum resolution within its superconducting gap. To understand the experimental data, we develop a tight binding model with 1/4 charge density wave (CDW) folding to calculate quasiparticle interference (QPI) features. We determine the QPI features are contributed solely by the K1 band observed in previous ARPES experiments [2]. With the band structure, we establish a detailed k - q space correspondence between the Fermi surface and QPI features, allowing for momentum resolved measurements of the superconducting gap structure at all available k points. Our measurements reveal that for the band accessible via STS, the superconducting gap is uniform at these special k points. Additionally, we track the energy dependence of the various CDW ordering features and demonstrate the 3/4 CDW exhibits unique behavior compared with the 1/4 and 1/2 CDWs, indicating that the 3/4 CDW may be sensitive to more bands than just K1.
Refs:
- K. Jiang, et al, Kagome superconductors AV3Sb5 (A = K, Rb, Cs), National Science Review 10, 10.1093/nsr/nwac199 (2022).
- M. Kang, et al, Twofold van hove singularity and origin of charge order in topological kagome superconductor csv3sb5, Nature Physics 18, 301 (2022).
Shruti Puri Group
Kaavya Sahay, Graduate Student
kaavya.sahay@yale.edu
Error Correction of Transversal CNOT Gates
Recent experimental advances in quantum error correction (QEC) have made it possible to implement logical multi-qubit transversal gates on QEC codes such as the surface code. A transversal controlled-NOT (tCNOT) gate on two surface codes introduces correlated errors across the code blocks and thus requires modified error correction procedures compared to established methods of correcting surface code quantum memories (SCQMs). Here, we examine and benchmark the performance of three different decoding and correction strategies for the tCNOT for scalable, fault-tolerant quantum computation. In particular, we present a low-complexity decoder based on minimum-weight perfect matching (MWPM) that achieves the same threshold as the SCQM. Our investigation builds towards systematic estimation of the cost of implementing large-scale quantum algorithms based on transversal gates in the surface code.
Helen Caines and Laura Havener Group
Andrew Tamis, Graduate Student
morgan.knuesel@yale.edu
Relativistic Heavy Ion Group @ Yale
Relativistic heavy ion physics is of international and interdisciplinary interest to nuclear physics, particle physics, astrophysics, condensed matter physics, and cosmology. The primary goal of this field of research is to recreate in the laboratory a new state of matter, the quark-gluon plasma (QGP), which is predicted by the Standard Model of particle physics (Quantum Chromodynamics) to have existed ten-millionths of a second after the Big Bang and may exist in the cores of very dense stars.
The research activities of the Relativistic Heavy Ion Group at Yale are centered at Yale, but involve experimental research on the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) on Long Island, New York, and on the ALICE experiment with heavy ions at the Large Hadron Collider (LHC) located at the Center for European Nuclear Research (CERN) in Geneva, Switzerland. Both experiments seek to form and investigate the QGP. The Yale Relativistic Heavy Ion Group is also involved in several R&D projects with a focus on detectors for the ePIC experiment at the Electron-Ion Collider (EIC), soon to be under construction at BNL.
Leonid I. Glazman Group
Nemin Wei, Postdoctoral Associate
nemin.wei@yale.edu
Dirac-point spectroscopy of flat-band systems with the quantum twisting microscope
Motivated by the recent development of the quantum twisting microscope, we formulate a theory of elastic momentum-resolved tunneling across a planar tunnel junction between a monolayer graphene layer situated on a tip and a twisting graphene-based sample. We elucidate features in the dependence of the tunnel current on bias and twist angle, which reflect the sample band structure and allow the tip to probe the momentum-and energy-resolved single-particle excitations of the sample. We specifically compute the low-temperature tunneling spectrum of magic angle twisted bilayer graphene (MATBG) rotated relative to the tip by nearly commensurate angles, highlighting the potential of Dirac-point spectroscopy to measure single-particle spectral functions of flat bands along specific lines in reciprocal space. Furthermore, our analysis of tunneling matrix elements suggests a method to extract the information about electron wave functions from the tunneling spectrum. Finally, we discuss signatures of C3z symmetry breaking in the tunneling spectrum using strained MATBG as an example. Our work establishes a general theoretical framework for Dirac-point spectroscopy of flat-band systems using the quantum twisting microscope.
Jack Harris Group
Igor Brandão, Graduate Student
igor.brandao@yale.edu
Optomechanics Inside a Levitated Superfluid Helium-4 Drop
Center of mass motion of levitated solids in high vacuum [1] and bulk modes of solid-state mechanical devices [2] have enabled quantum control over micromechanical systems. Here, we present ongoing experiments expanding the scope of coherent control to shape oscillations of liquid microdrops coupled to their optical whispering gallery modes (WGMs). Thus, our optomechanical platform is entirely hosted inside a magnetically levitated superfluid Helium-4 drop.
Trapping in ultrahigh vacuum (≤ 3×10-11 mbar) provides environmental isolation, passive evaporative cooling to sub-Kelvin temperatures, and means for the liquid’s surface tension to mold itself into a highly spherical shape. We have measured the frequencies of oscillation of the drop's free surface with agreement to ~ 1 part in 104 with ab initio theory, providing precise measurement of its diameter (up to 0.8 mm), evaporation rate (≥ 0.3 pm/s) and bulk temperature (~ 270 mK).
The spherical geometry allows for standing waves of light to exist within the dielectric drop, WGMs, serving as our optical cavity. We find that free-space laser beams couple to a variety of WGMs over a wide range of drop sizes. By modulating their optical paths with coherently driven surface oscillations, we have observed WGMs with Finesses up to 1000, characterized their linewidths and polarization dependence, and calibrated the absolute amplitude of the surface oscillation (≤ 5 nm). Ab initio calculations, however, also predict yet unobserved ultrahigh Finesse WGMs (F>107) [3].
Our ongoing efforts focus on enhanced detection of higher-finesse WGMs, and to quantify their single photon optomechanical coupling strength with the drop’s surface oscillations, theoretically predicted to surpass the mechanical frequency [3].
Bibliography:
- Science 367, 892 (2020)
- Phys. Rev. Lett. 130, 133604 (2023)
- Phys. Rev. A 96, 063842 (2017)
Karsten Heeger Group
Talia Weiss, Graduate Student
talia.weiss@yale.edu
Project 8 Neutrino Mass Experiment
This poster provides an overview of the Project 8 experiment, which aims to determine the absolute neutrino mass scale from the shape of the tritium beta decay spectrum near its endpoint. For this purpose, the collaboration developed a frequency-based technique for measuring electron energies: Cyclotron Radiation Emission Spectroscopy (CRES). This poster covers Project 8's first upper limit on the neutrino mass, an apparatus being commissioned to demonstrate sub-eV (~10ppm) electron energy resolution, and a future apparatus with an atomic tritium source.
Nir Navon Group
Songtao Huang, Graduate Student
gabriel.assumpcao@yale.edu
Quantum Simulation with Ultracold Fermions in Programmable Potentials
For the past two decades harmonically trapped ultracold atomic gases have been used with great success to study fundamental many-body physics in flexible experimental settings. However, the resulting gas density inhomogeneity in those traps makes it challenging to study paradigmatic uniform-system physics (such as critical behavior near phase transitions) or complex quantum dynamics .The realization of homogeneous quantum gases trapped in optical boxes has marked a milestone in the quantum simulation program with ultracold atoms. In this poster, we will present an overview of our recent experimental work at Yale, which include the emergence of sound with tunable interactions, loss dynamics due to near-resonant light in the BEC-BCS crossover, and the recombination dynamics and energetics of a three-component Fermi gas.
Karsten Heeger Group
Tyler Stokes, Postdoctoral Associate
tyler.d.stokes@yale.edu
Probing the Universe with the Deep Underground Neutrino Experiment (DUNE)
The Deep Underground Neutrino Experiment (DUNE) is an international collaboration of over 1,000 researchers which will study neutrinos and search for phenomena beyond the Standard Model (BSM). DUNE will employ liquid argon time projection chambers (LArTPCs) containing 70 ktons of LAr, 40 ktons of which are active, located more than a kilometer underground at the Sanford Underground Research Facility. The high spatial imaging resolution capabilities of LArTPCs, combined with the large detector volume and underground location allow DUNE to study neutrinos and rare processes by reducing cosmogenic backgrounds.
This poster highlights Yale’s contributions to DUNE, spanning detector development, involvement in the ProtoDUNE prototype program, and Far Detector physics studies with atmospheric neutrinos and rare process searches such proton decay. These efforts reflect Yale’s role in both hardware development and physics analysis as the experiment moves toward installation and operation in the coming years.
Charles Brown Group
Rafaella Zanetti, Graduate Student
raffaela.zanetti@yale.edu
Building an Optical Quasicrystal of Ultracold Lithium
We use ultracold lithium-7 and -6 atoms in optical aperiodic lattices to investigate the quantum properties of quasicrystals. Atoms cooled to near absolute zero temperatures are directly sensitive to quantum mechanical effects and exhibit unusual states of matter like Bose Einstein Condensates and Degenerate Fermi Gases. Quantum simulation uses one quantum system that is easier to control (Lithium) to simulate another (quasicrystals). Quasicrystals are materials with long-range order and rotational symmetry that is forbidden in periodic crystals, but without translation symmetry. Solid quasicrystals have more disorder and electron transport mechanisms that are difficult to understand analytically. By trapping our ultracold atoms in an optical lattice with a quasicrystalline configuration, we can simulate quasicrystal materials’ exotic quantum properties with our simpler system.
Jack Harris Group
Yilin Li, Graduate Student
yilin.li@yale.edu
Prospects for a superfluid whispering gallery mode optomechanical oscillator
Abstract to come.
Jack Harris Group
Gaurav Nirala, Postdoctoral Associate
yilin.li@yale.edu
Phonon Entanglement
in Macroscopic Optomechanical Oscillators
Abstract to come.