Poster Session Program OPEN HOUSE 2019 YALE PHYSICS Thursday, March - - PDF document

Thursday, March 28, 2019 1:20pm Sloane Physics Lab, 2nd Floor

OPEN HOUSE 2019 • YALE PHYSICS Poster Session Program

Kelly Backes kelly.backes@yale.edu Red 5 AMO Third Year Graduate Student with Steve Lamoreaux Univ Calif Berkeley Building a Squeezed State Receiver for the Haloscope at Yale Sensitive to Axion CDM (HAYSTAC) Experiment Mary Lou Bailey marylou.bailey@yale.edu Light Green 9 Biophysics Fourth Year Graduate Student with Simon Mochrie University of California, Santa Barbara Investigating dynamic chromatin states in a model cell organism Robby Blum robbyblum@gmail.com Light Green 6 Biophysics Seventh Year Graduate Student with Sean Barrett University of Maryland, College Park NMR observations of discrete time crystalline signatures in an ordered crystal of ammonium dihydrogen phosphate Hannah Bossi hannah.bossi@yale.edu Light Blue 3 Nuclear Physics First Year Graduate Student with John Harris Colby College Probing the Quark-Gluon Plasma with Jets Jacob Curtis jacob.curtis@yale.edu Purple 1 Applied Physics Second Year Graduate Student with Rob Schoelkopf University of Michigan Simulation of molecular vibronic spectra in cQED Chris Davis christopher.davis@yale.edu Orange 4 High Energy/Particle Physics Sixth Year Graduate Student with Reina Maruyama Texas A&M University The Cryogenic Underground Observatory for Rare Events Arpit Dua arpit.dua@yale.edu Purple 5 Applied Physics Fifth Year Graduate Student with Liang Jiang Indian Inst of Tech - Roorkee Spurious topological entanglement entropy and subsystem symmetries in compactified cubic code Alec Eickbusch alec.eickbusch@yale.edu Purple 2 Applied Physics Second Year Graduate Student with Michel Devoret The University of Texas, Austin Quantum error correction using grid states of a microwave resonator Paul Fanto paul.fanto@yale.edu Yellow 2 Condensed Matter Fourth Year Graduate Student with Yoram Alhassid Princeton University Quantum Many-Body Systems at Finite Temperature: The Static-Path Plus Random-Phase Approximation Nicholas Frattini nicholas.frattini@yale.edu Purple 4 Applied Physics Fourth Year Graduate Student with Michel Devoret University of California, Berkeley Stabilizing a Protected Qubit in a Superconducting Kerr Nonlinear Resonator

Sean Frazier sean.frazier@yale.edu Red 2 AMO Second Year Graduate Student with Jack Harris Princeton University Quantum Optomechanics with Superfluid Helium Jeremy Gaison jeremy.gaison@yale.edu Orange 3 High Energy/Particle Physics Fourth Year Graduate Student with Karsten Heeger Drexel University Precision Neutrino Measurements with PROSPECT Ziad Ganim ziad.ganim@yale.edu Light Green 10 Biophysics Assistant Professor of Chemistry with Massachusetts Institute of Technology Force-Detected Absorption Spectroscopy in Solution With Optical Tweezers Sumita Ghosh sumita.ghosh@yale.edu Light Blue 1 Nuclear Physics Third Year Graduate Student with David Moore University of California, Berkeley Search for Millicharged Dark Matter Particles Using Optically Trapped Microspheres Ako Jamil ako.jamil@yale.edu Light Blue 2 Nuclear Physics Second Year Graduate Student with David Moore University of Erlangen-Nuremberg in Germany and Stanford University, CA nEXO - Search for Neutrinoless Double Beta Decay Scott Jensen scott.jensen@yale.edu Yellow 3 Condensed Matter Sixth Year Graduate Student with Yoram Alhassid Northeastern Univ (Boston) Nature of Pairing Correlations in the Homogeneous Fermi Gas at Unitarity Nirag Kadakia thierry.emonet@yale.edu Light Green 2 Biophysics Postdoctoral Associate with Thierry Emonet University of California, San Diego Combinatorial odor coding and the logic of olfactory navigation through biophysical modeling, machine learning, and optogenetics Keita Kamino thierry.emonet@yale.edu Light Green 4 Biophysics Postdoctoral Associate with Thierry Emonet University of Tokyo Probing the principles of cellular information processing Nenad Kralj nenad.kralj@yale.edu Red 3 AMO Postdoctoral Associate with Jack Harris University of Camerino, Italy Exceptional Points and Topological Energy Transfer in Optomechanical Systems Emily Kuhn emily.kuhn@yale.edu Navy 4 Astrophysics/Cosmology Third Year Graduate Student with Laura Newburgh Duke University Calibration Instrumentation for the Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) Tyler Lutz tyler.lutz@yale.edu Yellow 1 Condensed Matter Fifth Year Graduate Student with John Wettlaufer University of California, Berkeley; ETH Zürich; University of Chicago Nonlocal Mixing from Stochastic Advection

Zhe Mei zhe.mei@yale.edu Light Green 11 Biophysics Third Year Graduate Student with Corey O'Hern Bard College Computational Protein Redesign Using NMR Structures James Nikkel james.nikkel@yale.edu Orange 2 High Energy/Particle Physics Associate Research Scientist with Karsten Heeger Kent State University Yale Wright Laboratory: Transforming Discovery James Nikkel james.nikkel@yale.edu Orange 1 High Energy/Particle Physics Associate Research Scientist with Karsten Heeger Kent State University The Advanced Prototyping Center Dorottya Noble dorottya.noble@yale.edu Light Green 1 Biophysics Director with Integrated Graduate Program in Physical and Engineering Biology Ryan Petersburg ryan.petersburg@yale.edu Navy 3 Astrophysics/Cosmology Fourth Year Graduate Student with Debra Fischer University of North Carolina, Chapel Hill Aluminum Nitride Microchip Frequency Comb to Advance Exoplanet Discovery Mariel Pettee mariel.pettee@yale.edu Orange 7 High Energy/Particle Physics Fourth Year Graduate Student with Sarah Demers Harvard University The VH, H->tau tau Search with the ATLAS Detector Jared Rovny jared.rovny@yale.edu Light Green 7 Biophysics Sixth Year Graduate Student with Sean Barrett University of Dallas Beyond discrete time crystal signatures: hidden coherence, causes of decay, and the first ‘discrete time crystal echo’ Luis Saldana luis.saldana@yale.edu Orange 6 High Energy/Particle Physics Sixth Year Graduate Student with Karsten Heeger Georgia Inst of Technology Project 8: Toward a Radio-Frequency Measurement

• f the Neutrino Mass

Lauren, Saunders lauren.saunders@yale.edu Navy 2 Astrophysics/Cosmology Second Year Graduate Student with Laura Newburgh University of Chicago Data Acquisition and Control Systems for the Simons Observatory Daniel Seara daniel.seara@yale.edu Light Green 3 Biophysics Fourth Year Graduate Student with Michael Murrell New York University Entropy production rates in particles, fields, and cells William Sweeney william.sweeney@yale.edu Purple 6 Applied Physics Seventh Year Graduate Student with Doug Stone University of Chicago Perfectly Absorbing Exceptional Points and Chiral Absorption

James Teoh james.teoh@yale.edu Purple 7 Applied Physics Second Year Graduate Student with Rob Schoelkopf Imperial College Of London On Demand Quantum State Transfer and Entanglement Between Remote Microwave Cavity Memories William Thompson william.thompson@yale.edu Orange 8 High Energy/Particle Physics Fourth Year Graduate Student with Reina Maruyama Wake Forest University Searching for Dark Matter with COSINE-100 Jack Treado john.treado@yale.edu Light Green 5 Biophysics Third Year Graduate Student with Corey O'Hern Georgetown University Jamming, percolation and complexity in proteins Chris Wang christopher.wang@yale.edu Purple 1 Applied Physics Fourth Year Graduate Student with Rob Schoelkopf University of Pennsylvania Simulation of molecular vibronic spectra in cQED Yiqi Wang yiqi.wang@yale.edu Red 4 AMO Second Year Graduate Student with Jack Harris Fudan University, Shanghai, China Levitated Optomechanics with a Superfluid Helium Drop Christian Weber christian.weber@yale.edu Orange 5 High Energy/Particle Physics Fifth Year Graduate Student with Keith Baker Technical University of Berlin Electron E-p combination - improved electron energy resolution through combination of tracker and calorimeter information Peter Williams peter.williams@yale.edu Light Green 8 Biophysics Fourth Year Graduate Student with Corey O'Hern Colgate University Globular Collapse and Dynamics of Polymers with Explicit Active Pullers Trevor Wright trevor.wright@yale.edu Red 1 AMO First Year Graduate Student with David DeMille Amherst College CeNTREX - A Tabletop Experiment Searching for Nuclear Time Reversal-Violating Physics Luna Zagorac jovana.zagorac@yale.edu Navy 1 Astrophysics/Cosmology Third Year Graduate Student with Nikhil Padmanabhan Colgate University Gravitational Wave Spectrum of Ultralight Primordial Black Holes Xiaoyu Zhang xiaoyu.zhang@yale.edu Purple 3 Applied Physics First Year Graduate Student with Peter Schiffer Rutgers University & University of Illinois, Urbana- Champaign Magnetic Frustration at the Nanoscale

Abstracts

Building a Squeezed State Receiver for the Haloscope at Yale Sensitive to Axion CDM (HAYSTAC) Experiment

Kelly Backes Department of Physics, Yale University, New Haven, Connecticut, 06520, USA. Email: Kelly.backes@yale.edu The axion originally was postulated as a solution to the strong CP problem and serves as potential solution to the dark matter problem. HAYSTAC is a dark matter haloscope looking for axions in the 20 𝜈eV mass decade and has excluded axions in the range 23.15 < 𝑛𝑏 < 24.0 𝜈eV. The experiment is comprised of a high Q microwave cavity immersed in a 9 T magnetic field where axions are converted to microwave photons. The microwave frequency where HAYSTAC operates is particularly adapted to exploit the tools of quantum

• metrology. Advances in these tools have led to unprecedented degrees of microwave squeezing

which can be exploited to speed up the search for axion dark matter. HAYSTAC is being upgraded to include such a squeezed state quantum receiver which will allow it to reduce background noise to below vacuum and speed up the rate at which it can search for axions by a factor of 2.3. This squeezed state receiver is comprised of two Josephson parametric amplifiers (JPAs), one of which generates a squeezed state which is injected into an overcoupled microwave cavity where cavity coherent noise is added to it. The second JPA serves as the readout and amplifies the signal before it is digitized. This poster will focus on the design of the experiment and the current progress made towards implementing the squeezed state receiver.

Investigating dynamic chromatin states in a model cell organism

Mary Lou P. Bailey1,2, Jessica Johnston3, Megan C. King2,3, Simon G. J. Mochrie1,2,4

1Department of Applied Physics, Yale University, 2Yale University Integrated Graduate Program in Physical and

Engineering Biology, 3Department of Cell Biology, Yale School of Medicine, 4Department of Physics, Yale University P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: Marylou.bailey@yale.edu

Chromatin’s biological functions are inextricably linked to its spatial organization and real-time

• dynamics. I will describe research aimed at gaining new insight into chromatin organization and

dynamics, focused on the emerging model of Topologically-Associated Domains (TADS) – 50-100 kb- length regions of the genome that show unusually high contact probability. To date, approaches capable of linking the physical TAD structure to chromatin dynamics have been lacking. I will present a novel data acquisition and analysis pipeline and preliminary results: We label specific gene loci within a model cell organism, S. pombe, with lacO arrays bound by fluorescent LacI-GFP proteins. We then image cell populations over time on a widefield microscope. These movies are used to track the motions of loci for large populations of single cells. Next, we analyze the diffusive behavior of the chromatin loci by determining the mean-square displacement and velocity autocorrelation function. To further investigate the underlying biology that contributes to locus motion, we compare perturbations to a variety of biological inputs, including temperature, the cytoskeleton, and proteins that are hypothesized to have key roles in TAD formation. We acknowledge support of the NSF via EFRI and the NSF GRFP

NMR observations of discrete time crystalline signatures in an

• rdered crystal of ammonium dihydrogen phosphate

Jared Rovny, Robert Blum, Sean Barrett

The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of

• America. Email: robert.blum@yale.edu

The phase structure of driven quantum systems can include exotic phenomena, including the recently- described discrete time crystal (DTC), which is a robust phase that breaks the discrete time translation symmetry of its driving Hamiltonian. If the driving Hamiltonian has period T, the key signature of a DTC is a response which instead has period nT (with n = 2, 3, 4, …), which is robust to variation of the pulse angle θ near π. Two experiments recently demonstrated this signature, one in trapped ions [1], and the other in diamond NV centers [2]. Here, we show signatures of DTC order [3,4] in an NMR system of 31P spins in an oriented crystal of ammonium dihydrogen phosphate (ADP), with chemical formula NH4H2PO4. To see the DTC signatures, we “drive” the system with repeated pulses of angle θ = π + ϵ, with delays of time τ between the pulses (the “DTC sequence”). For long-enough delays τ between pulses, we have observed strictly “up-down” oscillations of the magnetization, even when we have intentionally adjusted the pulse angle away from π. By exploring where “up-down” oscillations are observable without “breaking” into a beating pattern, we can define a region in (θ, τ) space where the behavior is robust. We study the shape of this “DTC region” both with and without CW decoupling applied to the protons, turning the 1H-31P coupling “off” and “on”

• selectively. This is the first DTC experiment with up to three spin species in the effective spin Hamiltonian.

Moreover, the long T1 time of 31P spins in ADP allows us to explore this behavior for very long τ, allowing up to 1 second between pulses in the absence of CW decoupling. Compared to the earlier trapped ion and NV center experiments, we observe robust DTC oscillations across a much greater range in (θ, τ) than has been observed to date. This result, combined with the high-degree of order in our spin Hamiltonian, poses many interesting questions for the theory of DTC physics. We will describe how these DTC experiments are both similar to, and different from, familiar NMR sequences. [1] J. Zhang et al., Nature 543, 217 (2017) [2] S. Choi et al., Nature 543, 221 (2017) [3] J. Rovny, R. Blum, and S. Barrett, PRL 120, 180603 (2018) [4] J. Rovny, R. Blum, and S. Barrett, PRB 97, 184301 (2018)

Probing the Quark-Gluon Plasma with Jets

Hannah Bossi for the Yale Relativistic Heavy Ion Group

The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of

• America. Email: hannah.bossi@yale.edu<mailto:hannah.bossi@yale.edu>

In the microseconds immediately following the Big Bang, the universe existed as a state of hot and dense matter in which quarks and gluons are deconfined called the quark-gluon plasma (QGP). These extreme conditions are reproducible in laboratory settings with the collisions of relativistic heavy ions. Through studying the quark-gluon plasma, we can gain insight into fundamental mysteries of the strong interaction: confinement, chiral-symmetry restoration, and more. Two detectors which are optimized to study heavy ion collisions are ALICE (A Large Ion Collider Experiment) and STAR (Solenoid Tracker at RHIC). High transverse momentum (𝑞𝑈) partons, produced early in the collision before QGP formation fragment and hardonize into a collimated spray of particles called a jet. As jets experience the full evolution of the medium, they are the ideal candidates to probe the QGP. However, a major obstacle in reconstructing jets in heavy ion collisions is the large amount of background. A novel approach to extract jets from this background is to use machine learning techniques. Although this necessitates further study, early results

• f this approach look promising.

Simulation of molecular vibronic spectra in cQED

• C. S. Wang, J. C. Curtis, B. J. Lester, Y. Y. Gao, Y. Zhang, L. Frunzio, M. H. Devoret, L. Jiang, S. M. Girvin, R.
• J. Schoelkopf

The Departments of Physics and Applied Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: christopher.wang@yale.edu and jacob.curtis@yale.edu

Recent cQED experiments have demonstrated high fidelity preparation, manipulation, and measurement

• f quantum information stored in high-Q 3D microwave cavity modes. This platform is well-suited for fault

tolerant quantum computation using hardware efficient error-correction bosonic codes. Additionally, there has been interest in using quantum computers to simulate problems in quantum chemistry, such as electronic and vibrational structure problems. These problems are inherently fermionic or bosonic and require additional mappings to be simulated digitally on qubit-based quantum computers. A cQED system can be used as a “bosonic processor” to directly and efficiently simulate interesting many-body bosonic systems without having to map Hamiltonians onto qubit Pauli operators. Here, we use a two mode cQED device to simulate the vibronic structure of two vibrational modes of a molecule.

The Cryogenic Underground Observatory for Rare Events

Christopher Davis, Danielle Speller, Pranava Teja Surukuchi, Karsten Heeger, Reina Maruyama The Cryogenic Underground Observatory for Rare Events (CUORE) is a neutrinoless double-beta (0νββ) decay experiment currently in operation at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. Since April 2017, CUORE has been taking data in 130Te by using 988 TeO2 crystals arranged in 19 towers inside

• f a cryostat operating at approximately 10 mK. The current best limits from CUORE find

T1∕20ν > 1.5 × 1025 yr (90% C.L.), which is the most stringent limit to date on this decay in 130Te.

"The Department of Physics, Yale Unviersity, P.O. Box 201820, New Haven, Connecticut, 06520, United States of

• America. Email: christopher.davis@yale.edu@yale.edu<mailto:christopher.davis@yale.edu>"

Spurious topological entanglement entropy and subsystem symmetries in compactified cubic code

Arpit Dua, Dominic J. Williamson, and Meng Cheng

The Department of Physics, Yale Unviersity, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. arpit.dua@yale.edu

We demonstrate that linear combinations of subregion entropies with canceling boundary terms, commonly used to calculate the topological entanglement entropy, may suffer from spurious nontopological contributions even in models with zero correlation length. These spurious contributions are due to a specific kind of long-range string order, and persist throughout certain subsystem symmetry-protected phases. We introduce an entropic quantity that measures the presence of such order, and hence should serve as an order parameter for the aforementioned

• phases. Compactified cubic code is an example of a model that suffers from such spurious

contributions for certain values of compactification radii when the model has unbroken rigid 1D subsystem symmetries. We do a bulk computation of the topological entanglement entropy from a linear combination of subregion entropies with cancelling boundary terms and find such spurious contributions.

Quantum error correction using grid states of a microwave resonator

• A. Eickbusch, P. Campagne-Ibarcq, S. Touzard, E. Zalys-Geller, N.E. Frattini, V.V. Sivak, S. Puri, M.

Mirrahimi, S. Shankar, M.H. Devoret Yale Department of Applied Physics, 15 Prospect Street, Becton Center 401, New Haven, CT 06511, United States of America. Email: alec.eickbusch@yale.edu Quantum computation requires that systems preserve quantum information in the presence of noise. The impact of this noise can be mitigated by redundantly encoding a quantum bit of information within a space with a large number of dimensions. Stabilization is done by detecting noise-induced transformations of the system state before the encoded information is lost. In 2001, Gottesman Kitaev and Preskill (GKP) proposed to encode a quantum bit in non-local grid states of a harmonic oscillator. Remarkably, GKP codes have the potential to protect quantum information against all known error

• channels. Using a tunable interaction between an ancilla qubit and a microwave resonator, we have

implemented a short memory feedback protocol allowing for stabilization of GKP grid states.

Quantum Many-Body Systems at Finite Temperature: The Static- Path Plus Random-Phase Approximation

Paul Fanto and Yoram Alhassid Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, USA. Email: paul.fanto@yale.edu<mailto:paul.fanto@yale.edu> The calculation of thermal properties of strongly interacting quantum many-body systems presents a major challenge. Exact configuration-interaction methods are limited by the combinatorial growth of the many-particle model space with the number of particles. Mean- field approximations, which replace the interacting system with an effective system of non- interacting particles moving in a mean-field potential, are widely used but neglect important

• correlations. The Hubbard-Stratonovich path-integral representation of the Gibbs operator

provides a useful framework in which a hierarchy of approximations beyond the mean field can be developed. Within this framework, thermal properties can be calculated exactly to within a controllable statistical error using the auxiliary-field Monte Carlo (AFMC) method. However, AFMC calculations are computationally intensive and limited to interactions with good Monte Carlo sign. The static-path plus random-phase approximation (SPA+RPA) includes large- amplitude static fluctuations and small-amplitude time-dependent quantum fluctuations beyond the mean field. Although this approximation breaks down at very low temperatures, it has been shown to be accurate within its regime of validity. We review the application of this method within the Alhassid group to two different quantum many-body systems: ultrasmall metallic grains and atomic nuclei. We present recent results in atomic nuclei that show that the SPA+RPA recovers the enhancement to the entropy and the nuclear density of states due to collective rotational motion that is missing in the mean-field approximation. Finally, we discuss the planned development of this method for the nuclear many-body problem, as well as its potential applications to other strongly interacting quantum many-body systems.

Stabilizing a Protected Qubit in a Superconducting Kerr Nonlinear Resonator

N.E. Frattini*, A. Grimm*, S.O. Mundhada, S. Puri, S. Touzard, M. Mirrahimi, S. Shankar, M.H. Devoret

The Department of Applied Physics, Yale University, New Haven, Connecticut, 06520. Email: nicholas.frattini@yale.edu

Schrodinger cat states of microwave light based on superpositions of coherent states in a superconducting resonator can be used as error-protected qubits (quantum bits) as well as auxiliary systems for fault-tolerant quantum computation. It has recently been shown that applying a two-photon drive to a Kerr nonlinear resonator can stabilize such states. Here, we will give an introduction to this type of qubit and its potential uses in quantum computation before discussing and an experimental

• implementation. Our system is based on a modified, low-anharmonicity, transmon qubit acting as a

nearly harmonic oscillator. Instead of a single Josephson junction, we use a particular combination of Josephson junctions called a Superconducting Nonlinear Asymmetric Inductive eLement (SNAIL) that provides both three- and four-wave mixing Hamiltonian terms. This simultaneously implements the desired nonlinearity and gives us access to a strong two-photon drive. We will report on the details of this implementation as well as the realization of fast single-qubit gates and the increase in qubit coherence enabled in such a scheme.

Quantum Optomechanics with Superfluid Helium

Sean Frazier, Lucy Yu, Yogesh Patil, Jack Harris

The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of

• America. Email: jack.harris@yale.edu <mailto:jack.harris@yale.edu>

The field of optomechanics explores the interaction between electromagnetic radiation and mechanical motion. Researchers in the field pair optical cavities with mechanical resonators to form a cavity optomechanical system and consequently acquire a means to achieve quantum control over mechanical motion or, conversely, mechanical control over optical fields [1]. Our work focuses on optomechanics in a superfluid helium filled optical cavity. Superfluid helium has in recent years been demonstrated to be a very good platform to realize quantum optomechanics owing to its extremely low losses, both optical (it combines a ~19eV bandgap with a near total absence of chemical or structural defects) and mechanical (it has zero viscosity) [2]. Moreover, it offers access to the qualitatively novel and unexplored regime of fluid quantum optomechanics. Building on our previous work with superfluid helium filled fiber cavities, which couple an acoustic mode

• f the helium to an optical mode of the cavity [3], we present here work towards utilizing single photon

detectors for photon-phonon counting in such a device using a scheme modified and adapted from [4]. Additionally, we aim to conditionally prepare and detect a quantum non-Gaussian single-phonon state

• f this superfluid resonator.

[1] M. Aspelmeyer, T. J. Kippenberg, and F. Marquardt, Rev. Mod. Phys. 86, 1391 (2014) [2] A. D. Kashkanova et. al., Nat. Phys. 13, 74 (2017) [3] A. B. Shkarin et. al., arXiv 1709.02794 (2017) [4] R. Riedinger et. al., Nature 530, 313 (2016)

Precision Neutrino Measurements with PROSPECT Jeremy Gaison, Ben Foust, Danielle Norcini, Pranava Surukuchi, Tom Langford, James Nikkel, Arina Telles, Karsten Heeger

The Department of Physics, Yale Unviersity, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: jeremy.gaison@yale.edu

PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, is a 4 ton 6Li-doped liquid scintillator based detector designed to measure the antineutrino spectrum produced by nuclear fission at the High Flux Isotope Reactor at Oak Ridge National Laboratory. PROSPECT was built at Yale’s Wright Laboratory in order to make precision measurements of the neutrino spectrum of U-235 and to search for signatures of eV-scale sterile neutrinos. With the first 33 live days of data, we have excluded the sterile neutrino best fit of the reactor antineutrino anomaly at 2.2 sigma. I discuss the detector design, construction, deployment, and data analysis

• f the experiment.

Force-Detected Absorption Spectroscopy in Solution With Optical Tweezers

Jacob Black, Alexander Parobek, Qixuan Yu, Maria Kamenetska, Ziad Ganim

This fall, we are looking for a fearless student on the high-risk high-reward superresolution absorption spectroscopy project. ABSTRACT: Measuring absorption spectra of single molecules presents a fundamental challenge for standard transmission-based instruments because of the inherently low signal relative to the large background of the excitation source. Here we demonstrate a new approach for performing absorption spectroscopy in solution using a force measurement to read out optical excitation at the nanoscale.1 The photoinduced force between model chromophores and an optically trapped gold nanoshell has been measured in water at room

• temperature. This photoinduced force is characterized as a function of wavelength to yield the

force spectrum, which is shown to be correlated to the absorption spectrum for four model systems. The instrument constructed for these measurements combines an optical tweezer with frequency domain absorption spectroscopy over the 400-800 nm range. These measurements provide proof-

• f-principle experiments for force-detected nanoscale spectroscopies that operate under ambient

chemical conditions.

• 1J. Chem. Phys., 2018, 148(14), 144201. doi: 10.1063/1.5017853

Search for Millicharged Dark Matter Particles Using Optically Trapped Microspheres

Sumita Ghosh*, Fernando Monteiro, Gadi Afek, Andrew Kilby, and Wenqiang Li

The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of

• America. Email: sumita.ghosh@yale.edu

Models of dark matter where the particles carry a tiny electric charge (<< 1e) can arise from the presence

• f new forces in a hidden sector, which could mix weakly with Standard Model forces. Such stable

“millicharged” dark matter particles can be searched for if they become bound in matter. We use an

• ptical trap to measure the response to an applied electric field on an object with no net integer charge,

but which may contain such particles. This experiment has a fractional charge sensitivity of 10-4 electrons/√Hz for a wide range of millicharged particle masses, allowing exploration of uncharted regions

• f parameter space for such dark matter candidates.

Nature of Pairing Correlations in the Homogeneous Fermi Gas at Unitarity

Scott S. Jensen, Chris N. Gilbreth, Yoram Alhassid

“The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America, Email: scott.jensen@yale.edu”

Addressing the nature of pairing correlations in the two-species cold atomic Fermi gas at unitarity is a challenging many-body problem. The existence of a pseudogap regime separating the superfluid phase from the normal phase has been proposed but is still debated. To address this issue, we have calculated thermodynamic properties of the homogeneous unitary Fermi gas using finite-temperature auxiliary- field quantum Monte Carlo methods (AFMC) in the canonical ensemble on the lattice with a fixed filling factor 𝑤 = 0.06. We find no clear evidence of a pseudogap regime at unitarity. We further present AFMC calculations for the temperature dependence of Tan’s contact describing short-range pairing correlations for which we have taken the continuum limit. Our results provide remarkable agreement with the most recent high-precision ultracold atomic gas experiments of the MIT and Swinburne groups.

Combinatorial odor coding and the logic of olfactory navigation through biophysical modeling, machine learning, and optogenetics

Nirag Kadakia, Mahmut Demir, Adam Fine, Thierry Emonet Department of Physics; Department of Molecular, Cellular and Developmental Biology; and the Integrated Graduate Program in Physical and Engineering Biology; Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: thierry.emonet@yale.edu In olfactory systems, the identity of an odor is encoded by the specific pattern of activity it elicits across a population of olfactory receptor neurons (ORNs). The intensity and timing of odor cues can vary widely in natural environments, and odors can mix among one another, potentially scrambling these coding

• patterns. Our lab has investigated, using theory and experiment, how these confounds might be mitigated

by an adaptive scaling law recently observed in Drosophila olfactory receptor neurons, Weber’s Law of just-noticeable difference. We have shown that this single-neuron adaptive mechanism works in concert with circuit-level transformations to increase coding capacity and preserve neural representations of odor

• identity. Weber Law adaptation is versatile: it aids decoding fidelity both in decoding paradigms that

reconstruct exact odor signals, as well as those that classify odors more abstractly through learned

• association. More broadly, our work suggests that while Weber’s Law is known to help maintain sensitivity

in single-channel sensory systems (like chemotaxing bacteria), it can also benefit multi-channel systems in which neural tuning curves are highly overlapping. How do animals use these adaptable odor percepts to navigate their chemical environment? Odor environments are highly complex: they are dynamic and fluctuating, even turbulent, lacking well-defined concentration gradients. Our lab uses experiment, modeling, and data analysis to measure and quantify

• lfactory-driven behaviors in Drosophila. Part of this work involves developing machine learning-inspired

techniques to quantify behavioral strategies in odor environments. Another aspect involves understanding navigational strategies by precisely controlling olfactory stimuli through optogenetics. With optogenetics, we can perturb the coupling the between behavior and stimulus continuously, spanning a range of stimuli from naturalistic odor flows to artificial odor environments whose correlations are unlike anything typically encountered in nature. Unsurprisingly, the navigational strategies we are uncovering reflect a compromise of innate tendencies and flexible adaptation.

Probing the principles of cellular information processing

Keita Kamino, Thomas S Shimizu, Thierry Emonet The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: thierry.emonet@yale.edu Cells are information-processing devices. Extracellular signals (molecules, light, temperature and so

• n) detected by sensor molecules on the cell surface are processed, transduced, and responded to

through a network of biochemical reactions. A fundamental biological problem is to understand the principles governing such chemical reaction-based cellular computation. Unlike typical human- engineered computing devices, cellular signaling networks are highly variable and noisy: Two clonal (i.e., genetically-identical) cells may show substantially different responses to the same input due to differences in the abundances of system components (such as proteins). Furthermore, the same input delivered to a single cell gives rise to distributed responses due to the inherent stochasticity of chemical reactions. Although these two features of signaling networks – variation and noise – might be considered failures of quality control in a typical engineering set-up, they can be beneficial in biological contexts. Cells live in environments that are often unpredictable; therefore, diversifying responses in the population ensures that, in any environment, there is a subset of individuals that respond favorably and proliferates. More generally, to what extend biological systems use fluctuations to do useful work is unclear and a fundamental question in biophysics. To tackle these fundamental problems in cellular information processing, we study the best- characterized and mathematically-tractable model system for cellular information processing: The chemotaxis signaling network of bacterium E. coli, ‘the hydrogen atom’ of biology. E. coli cells use the chemotaxis signaling system to make measurements of their surroundings and move towards more favorable growth conditions, making accurate information transmission a matter of their survival. Recently, using a fluorescent microscopy technique called Förster resonance energy transfer (FRET) we have succeeded for the first time in directly measuring the output dynamics of the E. coli chemotaxis signaling network at the single-cell level. Furthermore, we have developed a ’programmable’ microfluidic to precisely control the temporal profiles of input stimuli delivered to

• cells. These technical

innovations ideally position us to tackle the long- standing problems of cellular information problems using notions developed in physical sciences, such as statistical mechanics and information theory.

• a. Input-stimulus control
• b. Single-cell output

Time (sec)

Output signal (FRET)

Microfluidics

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Calibration Instrumentation for the Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX)

Emily R. Kuhn, Laura B. Newburgh, Benjamin Saliwanchik

The Department of Physics, Yale University, P.O. Box 201820, New Haven, CT 06520, United States of America. Email: emily.kuhn@yale.edu

The Hydrogen Intensity Real-time Analysis eXperiment (HIRAX) is a 21cm intensity mapping experiment to be deployed in South Africa. It will consist of 1024 six meter parabolic dishes, and will map much of the southern sky over the course of four years. HIRAX will look near when the universe shifted from matter to dark energy dominated, a redshift range that is relatively unexplored; it will provide a new probe to better understand BAOs, at different redshifts and with different tracers than prior optical surveys; and it will dramatically expand the detection and understanding of fast radio bursts (FRBs). For HIRAX to achieve its science goals, it will need to overcome bright foregrounds, which requires precise characterization of the instrument. This poster will focus on two aspects of our instrument characterization: (1) noise temperature measurements and (2) drone beam mapping. To determine our antenna noise temperature, we have built a novel apparatus in which we use identical loads, one cryogenic and the other at room temperature, to take a differential measurement (y-factor measurement) to infer the noise of our system. Simulations predict this set up will allow us to understand our noise temperature to within 10%. The apparatus is currently being built in Wright Lab, and will be used to test current and future generations of

• feeds. Additionally, this poster will cover work on drone calibration measurements, which will be critical

to understanding our beams and controlling potential systematic errors. I will specifically touch on requirements to achieve accurate beam calibration and methods for checking in flight data sets for

• accuracy. I will also report initial data, and describe future plans.

Computational Protein Redesign Using NMR Structures

Zhe Mei, John Treado, Zachary Levine, Lynne Regan and Corey O’Hern

The Department of Physics, Yale University, P.O.Box 201820, New Haven, Connecticut, 06520, United States of

• America. Email: zhe.mei@yale.edu

A key aim of computational protein design is to understand how amino acid mutations affect the structure and stability of proteins. In this work, we construct a mutation dataset, which contains 32 pairs of single- core residue mutated crystal structures and their corresponding wildtype structures. We applied energy minimization using Charmm 36 force field to move the backbone and collective repacking to refine the side chain dihedral angles. Our method achieves a prediction rate of about 75% in terms of side chain dihedral angle accuracy. However, crystal structures might suffer from defects caused by the solid state

• environment. To improve the prediction accuracy, we propose to incorporate NMR structures in this method

given that NMR experiments yield conformations with more dynamics. We evaluate the local packing fraction and void geometry of the protein structures from NMR experiments. Although it was believed that NMR structures are nearly identical to crystal structures, we found that the core regions of NMR structures exhibit a more tightly packed geometry comparing to crystal structures. This packing geometry can be recapitulated with a minimal model of packing amino acid shaped particles in a box with temperature. This result agrees with the hypothesis that thermal fluctuation increases the hydrophobic effect.

Integrated Graduate Program in Physical and Engineering Biology

Dorottya Noble1,2, Thomas Pollard1,3, Simon Mochrie1,4,5, and Corey O’Hern1,4,6,7

• 1. Integrated Graduate Program in Physical and Engineering Biology; 2. Department of Molecular Biophysics

and Biochemistry; 3. Department of Molecular, Cellular and Developmental Biology; 4. Department of Physics;

• 5. Department of Applied Physics; 6. Department of Mechanical Engineering and Materials Science; 7.Graduate

Program in Computational Biology and Bioinformatics; Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: dorottya.noble@yale.edu Yale’s Integrated Graduate Program in Physical and Engineering Biology (PEB) trains students to apply experimental, computational and theoretical approaches from physics and engineering to address grand challenges in biology. Students enter into this certificate program from 11 different departments/tracks across Physics, Applied Physics, the School of Engineering and Applied Science, and the Biological and Biomedical Sciences umbrella program. They take PEB courses together, which have been integrated with departmental requirements. In these courses, they not only learn about quantitative methodology and approaches and how those are applied in biology, but also improve their cross-disciplinary communication skills. PEB also provides additional enrichment

• pportunities, which include 1) actively and regularly participating in the NSF international Physics of Living

Systems Research Network; 2) yearly travel funds to support attending conferences, meetings and workshops; 3) learning about various career tracks and networking with Physics, Biology, and Engineering PhDs through the PEB career series; 4) internal and external speaker series to hear about cutting edge biophysics research within Yale and at other institutions; and 5) participating in PEB outreach activities to increase diversity in STEM and gain skills in communicating with lay audiences.

Aluminum Nitride Microchip Frequency Comb to Advance Exoplanet Discovery

Ryan Petersburg, Alexander Bruch, Hong Tang, and Debra Fischer The Department of Physics, Yale Unviersity, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: ryan.petersburg@yale.edu<mailto:ryan.petersburg@yale.edu> The Extreme Precision Spectrograph (EXPRES), installed at the Discovery Channel Telescope, is a flagship echelle spectrograph capable of discovering minute exoplanet signals in the radial velocities (RVs) of potential host stars. In order to reach the 10 cm/s RV precision necessary to detect Earth-like exoplanets, EXPRES requires an ultra-precise laser frequency comb (LFC) that acts as a stable wavelength ruler around which the star’s absorption lines oscillate. EXPRES currently uses an LFC designed by Menlo Systems; however, this device is exorbitantly complex, since it uses cascading optical filters to down-sample a 250 MHz mode-locked laser to the 14 GHz free spectral range (FSR) required by EXPRES’s resolution, and does not reliably calibrate wavelength shorter than 500 nm due to limitations in its photonic crystal fiber. Therefore, in collaboration with the Yale Nanodevices Laboratory, we are testing LFCs based on Aluminum Nitride (AlN) microchips for use with EXPRES. AlN is an advantageous material because it can be easily fabricated into compact chips, it has strong second-order optical nonlinearity, and it has the widest-known spectral bandgap among all semiconductors, even reaching into the UV (shorter than 400 nm). Using an AlN microring, we imaged a 500 GHz FSR LFC with EXPRES and are currently using this data to model the point spread function of the instrument, enabling advanced methods of image processing, such as spectro-perfectionism, in the EXPRES data pipeline. We are also currently testing an LFC design that combines a supercontinuum-generating AlN waveguide with an infrared electro-optic modulation comb. With its simple design and small footprint, this next- generation LFC could change the landscape of extreme precision RV measurement.

Beyond discrete time crystal signatures: hidden coherence, causes of decay, and the first ‘discrete time crystal echo’

Jared Rovny, Robert Blum, Sean Barrett

The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: jared.rovny@yale.edu<mailto:jared.rovny@yale.edu>

The phase structure of driven quantum systems can include exotic phenomena, including the recently-described discrete time crystal (DTC), which is a robust phase that breaks the discrete time translation symmetry of its driving Hamiltonian. If the driving Hamiltonian has period T, the key signature of a DTC is a response which instead has period nT (with n=2,3,4,…), even when the drive is imperfect. Two experiments recently demonstrated this signature, one in trapped ions [1], and the other in diamond NV centers [2]. We have shown this signature in an NMR system of 31P spins on a crystal lattice, where we use cross-polarization between 31P and 1H to rapidly repeat our experiments. We “drive” the system with repeated pulses of angle , with delays of time  between the pulses (the “DTC sequence”). For long- enough delays  between pulses, we have observed strictly “up-down” oscillations of the magnetization (so-called “DTC

• scillations”), even when  is adjusted slightly away from  [3,4].

As in prior experiments, we observe DTC oscillations that eventually decay. An open question has been the cause for this decay of the response. Here, we study these phenomena in more detail, with two main results. First, we devise a novel “DTC echo” sequence to probe the coherence in the system. We observe clear echoes, demonstrating that the original pulse sequence is driving coherence to unobservable parts of the density matrix. This indicates that the decay of the

• riginal signal is caused in part by coherent evolution.

Second, we study the observed decay for  = . After exhaustively ruling out experimental sources for this decay, we show that the action of the internal Hamiltonian during the pulses can produce this decay. We demonstrate the importance of the pulse duration by altering the original “DTC sequence,” using  pulses of difference phases. Since the pulse phase should not matter for perfect  pulses in the delta-function pulse approximation, this allows us to isolate the effect of the internal Hamiltonian during the pulses, which we find to be significant. This will be an important limitation for any experiment which strives to determine an ‘intrinsic’ lifetime for DTC order. [1] J. Zhang et al., Nature 543, 217 (2017). [2] S. Choi et al., Nature 543, 221 (2017). [3] J. Rovny, R.L. Blum, S.E. Barrett, PRL 120, 180603 (2018). [4] J. Rovny, R.L. Blum, S.E. Barrett, PRB 97, 184301 (2018).

Project 8: Toward a Radio-Frequency Measurement of the Neutrino Mass

K.M. Heeger (PI), J. A. Nikkel, Pranava T. Surukuchi, L. Saldaña, P. Slocum, A. Telles The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: luis.saldana@yale.edu The most sensitive direct method to establish the absolute neutrino mass is observation of the endpoint

• f the tritium beta-decay spectrum. Cyclotron Radiation Emission Spectroscopy (CRES) is a precision

spectrographic technique that can probe much of the unexplored neutrino mass range with O(eV)

• resolution. A lower bound of 𝑛(𝜉𝑓) ≳ 9(0.1) meV is set by observations of neutrino oscillations, while

the KATRIN Experiment – the current-generation tritium beta-decay experiment based on the MAC-E filter technique – will achieve a sensitivity of 𝑛(𝜉𝑓) ≲ 0.2 eV. The CRES technique aims to avoid the difficulties in scaling up a MAC-E filter-based experiment to achieve a lower mass sensitivity. Proect 8 takes a phased approach towards this goal where each phase is distinguished by the source of CRES electrons, either krypton, molecular tritium and finally atomic tritium, and the respective detector design. Current efforts focus on a measurement of the first ever CRES tritium spectrum in Phase II (where molecular tritium is housed in a waveguide supporting a single antenna) to new designs and engineering for the next two phases in which tritium free-space radiation will be captured by arrays of antennas in a much bigger

• volume. This phased absolute neutrino mass experiment has the potential to reach sensitivities down to

𝑛(𝜉𝑓) ≲ 40 meV with an atomic tritium source, well below the limit of current-generation kinematic experiments.

Data Acquisition and Control Systems for the Simons Observatory

Lauren J. Saunders, Laura B. Newburgh, Brian J. Koopman

The Department of Physics, Yale University, P.O. Box 201820, New Haven, CT 06520, United States of America. Email: lauren.saunders@yale.edu

The Simons Observatory will be a system of four new Cosmic Microwave Background (CMB) telescopes designed to improve constraints on inflation, measure the sum of the neutrino masses, probe dark energy, and usher in an era of using the CMB to search for new particles and axion dark matter. To achieve these science goals, the Simons Observatory will deploy a total of 60,000 detectors among four separate telescopes: 30,000 on a single high-resolution Large Aperture Telescope, and 10,000 on each of three smaller, refracting Small Aperture Telescopes. The observatory will utilize a new Observatory Control System (OCS) data acquisition and control system, which will be implemented across all four telescopes to control, monitor, and collect data from a wide range of housekeeping and detector readout systems. OCS is currently in development, with functionality for temperature monitoring and control purposes. It will soon be expanded to facilitate other telescope subsystems, including half-wave plate encoder readout and detector readout. While OCS is currently being developed specifically for the Simons Observatory, it is designed with scalability in mind, making it applicable to future CMB experiments, such as CMB-S4.

Perfectly Absorbing Exceptional Points and Chiral Absorption

William R Sweeney, Chia Wei Hsu, Stefan Rotter, A. Douglas Stone

“The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of

• America. Email: william.sweeney@yale.edu”

We identify a new kind of physically realizable exceptional point (EP) corresponding to degenerate coherent perfect absorption, in which two purely incoming solutions of the wave operator for electromagnetic or acoustic waves coalesce to a single state. Such non-Hermitian degeneracies can occur at a real-valued frequency without any associated noise or nonlinearity, in contrast to EPs in lasers. The absorption line shape for the eigenchannel near the EP is quartic in frequency around its maximum in any

• dimension. In general, for the parameters at which an operator EP occurs, the associated scattering matrix

does not have an EP. However, in one dimension, when the S matrix does have a perfectly absorbing EP, it takes on a universal one-parameter form with degenerate values for all scattering coefficients. For absorbing disk resonators, these EPs give rise to chiral absorption: perfect absorption for only one sense

• f rotation of the input wave.

On Demand Quantum State Transfer and Entanglement Between Remote Microwave Cavity Memories [1]

James Teoh, Luke Burkhart, Christopher Axline, Wolfgang Pfaff, Mengzhen Zhang, Kevin Chou, Philippe Campagne-Ibarcq, Philip Reinhold, Luigi Frunzio, Steven Girvin, Michel Devoret, Liang Jiang, Robert Schoelkopf The Department of Applied Physics, 15 Prospect St, Yale University, New Haven, Connecticut, 06511, United States of America.

james.teoh@yale.edu

Large quantum machines can benefit from a network architecture, where quantum communication channels between well-isolated subsystems are controlled on demand. One efficient communication scheme is direct, deterministic photon transfer as proposed in [2]. Utilizing RF-controlled parametric conversion, we realize this protocol between two remote millisecond-lifetime microwave cavity

• memories. We transfer a quantum bit between memories with high efficiency, achieving an average state

fidelity that exceeds the classical bound. Furthermore, we extend this scheme in order to half-transfer a photon, generating high-fidelity entanglement between the two remote cavities. Direct quantum state transfer suffers from photon loss in the transmission channel. Parametric conversion between microwave cavity memories and propagating photons allows for the deterministic transmission of multi-photon quantum states. These states can be made robust to photon loss. We encode a qubit within a subspace

• f definite parity—an error-correctable encoding—and transfer the state between memories. We

measure the transfer efficiency to be at a level where parity measurement and feedback would improve the average state fidelity. With modest technical improvements, we expect to reach a regime where this error detection and correction yields a fidelity exceeding that already achieved for a single-photon encoding. [1] Axline et al, Nature Physics 2018 [2] Cirac et al, PRL 1997

Searching for Dark Matter with COSINE-100

William Thompson, Estella Barbosa de Souza, Jay Hyun Jo, Reina Maruyama Department of Physics, Yale University, P.O. Box 201820, New Haven, CT 06520, USA Email: william.thompson@yale.edu Physicists and astronomers are convinced that over 25% of the energy contained in our Universe comes in the form of dark matter. Because of its abundant nature physicists have been on the hunt for dark matter particles for the past several decades, but only one experiment, DAMA/LIBRA, claims to have detected these particles. Adding to the confusion, the most sensitive dark matter detectors not only fail to observe the type of dark matter that DAMA claims to see but actually rules out its existence within most typically considered models of dark matter. Either our theoretical understanding of dark matter is incomplete, or the signal seen by DAMA is of a different origin and being misinterpreted as dark matter. The COSINE-100 experiment is performing a test of DAMA’s claim of dark matter discovery in order to resolve this long-standing dispute within the field. The core component of the COSINE-100 detector is an array of sodium iodide crystal detectors that serve as the target for dark matter interactions. As these dark matter interactions are exceedingly rare the detectors must be extremely radiopure, as radioactive decays can impede measurement of a dark matter signal. Atmospheric particle showers can also preclude

• bservation of a dark matter signal, leading us to place our detector 700 meters beneath a mountain in

South Korea to shield for these particles. In this poster, I will present an outline of the motivation behind the COSINE-100 experiment and an

• verview of the detector itself. I will then discuss some recent results from the experiment with a focus
• n projects taken on by students in our group. Last, I will discuss the future prospects of COSINE, including

a possible deployment at the South Pole.

Jamming, percolation and complexity in proteins

Jack Treado, Zhe Mei, Lynne Regan, Corey O’Hern

The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of

• America. Email: john.treado@yale.edu

Proteins are the cornerstone of molecular biology; cell function, behavior and evolution are all controlled in some way by the specific three-dimensional structure of individual proteins. Understanding the physics

• f how proteins find, maintain and change their structure is therefore vital for understanding biology as a
• whole. However, there are still fundamental gaps in a complete physical picture of protein structure. For

example, in de novo structure prediction, computational approaches are steadily impoving folding predictions, but are still poor at distinguishing physical from non-physical “decoy” protein designs. In our recent work, we have made several findings that suggest there are universal features of protein structures that can aid in developing a more accurate physical picture of protein structure. We have found that protein cores are structurally equivalent to random, jammed packings of free amino-acid-shaped particles prepared without a backbone. These packings share free volume distributions, void space and thermal properties with experimentally-characterized proteins, which is surprising given that they are prepared

• ut of equilibrium and without backbone connectivity. Using percolation theory, we have also shown that

the voids in both proteins and packings of amino acids are in the same universality class as voids in systems

• f randomly-placed monodisperse spheres. We are currently working to use these studies to characterize

native protein fluctuations, and to use these fluctuations to predict how a structure will change upon

• mutation. Additionally, proteins exist on a complex high-dimensional energy landscape with an

astronomical number of metastable states; we can begin to describe the mean-field properties of this landscape using packings of amino-acid-shaped particles in order to develop a more complete theoretical picture of proteins in general.

Levitated Optomechanics with a Superfluid Helium Drop

• C. D. Brown, Y. Wang, M. Namazi and J. G. E Harris

The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of

• America. Email: yiqi.wang@yale.edu

Abstract: Helium drops are model systems for addressing numerous outstanding questions in physics and

• chemistry. They provide a powerful tool to study classical and quantum fluid dynamics, and to

spectroscopically probe the dopants or study cold chemical reactions. Furthermore, helium drops are proposed to be excellent candidates for studies of quantum optomechanics. For quantum optomechanics, it is of significance to access a combination of low optical and mechanical loss, low temperature, and high- precision measurement. Superfluid helium uniquely offers several advantages together: vanishing optical absorption and viscosity, high thermal conductivity, and the ability to cool itself efficiently via evaporation, which helps accessing new regimes of quantum optomechanics. To minimize dissipative coupling to the environment, we have proposed the use of magnetic levitation to suspend a drop of liquid helium in vacuum with the goal of using the drop's optical whispering gallery modes (WGMs) and its surface waves as an optomechanical system, while relying on the drop's evaporation to maintain low temperature. Specifically, we will describe the formation and trapping of the drops, and their evaporative cooling in the trap to ~ 330 mK. We will also present measurements of the drops’ mechanical resonances, and of their

• ptical Mie resonances. These preliminary results demonstrate a promising path towards high optical

quality factors and strong opto-mechanical couplings in massive objects.

Electron E-p combination - improved electron energy resolution through combination of tracker and calorimeter information

Christian Weber, Keith Baker The Department of Physics, Yale Unviersity, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: Christian.Weber@yale.edu The energy of electrons in the ATLAS detector is determined from energy deposits in the electromagnetic

• calorimeter. A sophisticated calibration scheme based on multivariate regression and boosted decision

trees is used to infer the true value of the electron energy. The inner tracker can provide an independent measurement of the electron momentum, that is however not included in the standard calibration

• scheme. We present the implementation of a maximum likelihood-based method to combine tracker and

calorimeter measurements for the electron energy measurement that leads to an improved resolution.

Globular Collapse and Dynamics of Polymers with Explicit Active Pullers

Peter Williams, Ivan Surovtsev, Megan King, Simon Mochrie, Corey O’Hern The Department of Applied Physics, Yale Unviersity, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: peter.williams@yale.edu Many biopolymers are acted upon by active processes which consume energy in order to translate or remodel the polymer. This includes many processes relevant to the central dogma of molecular biology (the process by which the information contained in DNA is turned into proteins). These processes drive the polymers out of equilibrium and deviate from conventional polymer theory. There has been recent work theoretical and implicit computational work to understand the dynamics and configurations of active polymers. We introduce an explicit molecular dynamics model of a particle with an attractive interaction to the polymer and applying a constant tangential force. The dynamics of our model as characterized by the mean square displacements of individual monomers is consistent with the theoretical Active Rouse solution. Furthermore, we have shown that upon increasing activity, there is a dramatic drop in the radius of gyration of the polymers. This is manifested both by increasing the number of active pullers and/or increasing the magnitude of the active force. We have computed an effective Péclet number displaying universality of this collapse regardless of polymer length and the number of pullers. We hypothesize that this activity drives the globular segregation of chromosomes in the nuclear envelope. In future applications, this model can be adapted to more closely model loop extrusion of chromatin fiber and the effect of local volume exclusion of nascent transcripts via transcription.

CeNTREX – A Tabletop Experiment Searching for Nuclear Time Reversal-Violating Physics

David DeMille, Olivier Grasdijk, Jakob Kastelic, David Kawall (Umass Amherst), Steve Lamoreaux, Oskari Timgren, Konrad Wenz (Columbia University), Tristan Winick (Umass Amherst), Trevor Wright, Tanya Zelevinsky (Columbia University). CeNTREX Collaboration

The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of

• America. Email: trevor.wright@yale.edu

CeNTREX (Cold molecule Nuclear Time-Reversal Experiment) is a molecular-beam experiment aiming to investigate time reversal symmetry-violating interactions in TlF associated with the Schiff Moment of the Tl nucleus. This is to be achieved by measuring the change in the spin precession frequency of the Tl nucleus when changing between parallel and anti-parallel applied electric and magnetic fields. We project a 20-fold improvement in sensitivity to T-violating nuclear effects compared to current state of the art. A key part of our proposed experiment is the use of optical cycling to enable unit detection efficiency and, eventually, laser cooling of TlF. Recent measurements of excited-state hyperfine structure and vibrational branching ratios of the relevant optical transition in TlF, and their implications for optical cycling, are described.

Gravitational Wave Spectrum of Ultralight Primordial Black Holes

• J. Luna Zagorac, Richard Easther, Nikhil Padmamabhan

The Department of Physics, Yale University, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: luna.zagorac@yale.edu Tight constraints on the abundance of primordial black holes can be deduced across a vast range of masses, with the exception of those light enough to fully evaporate before nucleosynthesis. This hypothetical population is almost entirely unconstrained, to the point where the early Universe could pass through a matter-dominated phase with primordial black holes as the primary component. The

• nly obvious relic of this phase would be Hawking radiated gravitons which would constitute a

stochastic gravitational wave background in the present-day Universe, albeit at frequencies far beyond the scope of any planned detector technology. This poster explores the effects of classical mergers in such a matter dominated phase. For certain ranges of parameters, a significant fraction of the black holes merge, providing an additional, classical source of primordial gravitational waves. The resulting stochastic background typically has a lower amplitude than the Hawking background and lies at less extreme frequencies, but is unlikely to be easily detectable, with a maximal present-day density of ΩGW ∼ 10−12 and frequencies between 1015 − 1019 Hz. We also assess the impact of radiation accretion on the lifetimes of such primordial black holes and find that it increases the black hole mass by ∼ 14% and the lifetimes by about 50%. However, this does not qualitatively change any of our conclusions.

Magnetic Frustration at the Nanoscale

Xiaoyu Zhang, Nicholas S. Bingham, & Peter Schiffer The Department of Physics and Applied Physics, Yale Unviersity, P.O. Box 201820, New Haven, Connecticut, 06520, United States of America. Email: xiaoyu.zhang@yale.edu, nicholas.bingham@yale.edu, peter.schiffer@yale.edu Artificial spin ice systems (Figure 1) are two-dimensional arrays of nanomagnetic islands that are designed to study collective behavior of interacting magnetic systems. Such systems are lithographically fabricated so that we can control all aspects of the array geometry. Each island behaves as a single magnetic domain with its moment pointing along the long axis of the island and the array geometry results in frustration of the magnetic interactions between the islands. These systems are analogs to a class of magnetic materials in which the lattice geometry frustrates interactions between individual atomic moments, and in which a wide range of novel physical phenomena have been observed. We then utilize real-space imaging techniques such as photoemission electron microscopy and magnetic force microscopy to observe how individual nanomagnets behave. Our current work is focused on three areas: visualization of emergent behavior in the collective dynamics of the magnetic moments of vertex-frustrated systems which have degenerate ground states and movable excited vertices, the investigation of the magnetization reversal process and avalanches in artificial square ice, and electrical transport studies of connected networks of ferromagnetic nanowires. Figure 1: Square artificial spin ice. (a) Atomic force microscopy, (b) magnetic force microscopy, (c) magnetization map, from R. F. Wang et al., Nature 439, 303 (2006).