Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session Y33: Dynamics of Entanglement and Quantum Information |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Peng Chen, University of Arkansas Room: Room 225 |
Friday, March 10, 2023 8:00AM - 8:12AM |
Y33.00001: Majorana fusion in interacting one-dimensional Kitaev chains. bradraj pandey
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Friday, March 10, 2023 8:12AM - 8:24AM |
Y33.00002: Simulating correlation-spreading dynamics in the two-dimensional Bose-Hubbard model by the tensor-network method Ryui Kaneko, Ippei Danshita The recent developments of analog quantum simulators with cold atoms and trapped ions have required cross-checking the accuracy of quantum-simulation experiments using quantitative numerical methods. However, it is particularly challenging to simulate the dynamics of systems with more than one spatial dimension. Here we show that a tensor-network algorithm running on classical computers is practical for this purpose. Specifically, we analyze the dynamics of the two-dimensional Bose-Hubbard model after a sudden quench starting from a Mott insulator using the tensor-network method based on infinite projected entangled pair states (iPEPS). We have found that the single-particle correlation functions are in good agreement with a recent experiment. We also predict how phase and group velocities change in the intermediate interaction regime by extracting them from the single-particle and density-density correlation functions. These findings provide a quantitative benchmark for future experiments and numerical simulations. |
Friday, March 10, 2023 8:24AM - 8:36AM |
Y33.00003: Page curve like entanglement dynamics in a simple free fermion model Stefan Kehrein Reproducing the Page curve for the entanglement dynamics of an evaporating black hole is a major challenge in black hole physics. It is also an important step towards the resolution of the information paradox. I introduce a free fermion model with non-equilibrium quench dynamics that mimicks some features of the evaporation process. The time-dependent entanglement entropy of this model can be calculated exactly and shows Page curve like behavior. While one should be cautious to not overinterpret this analogy, one can draw lessons from it regarding the interpretation of Page curve like entanglement dynamics in quantum many-body systems. |
Friday, March 10, 2023 8:36AM - 8:48AM |
Y33.00004: Evolution of entanglement spectra under Rydberg-blockaded dynamics. Martin Schnee, Stefanos Kourtis Properly identifying and classifying the diverse non-equilibrium phases that isolated quantum many-body systems can exhibit is a major challenge. While focus is generally put on chaotic systems that rapidly thermalize, we investigate a constrained spin system, the so-called PXP model, which weakly breaks ergodicity. For some fine-tuned initial product states the dynamics is anomalously slow and coherence-preserving. We characterize the approach to equilibrium by probing how such initially disentangled state becomes entangled using random matrix-based diagnostics. |
Friday, March 10, 2023 8:48AM - 9:00AM |
Y33.00005: Measurement-only dynamics in the one-dimensional XY model Sarvesh Srinivasan, Zhen Bi Intriguing critical dynamics can appear by using frustrated measurements on a quantum state. For instance, performing random ZZ and X measurements on a 1D spin chain can induce a symmetry-breaking-like phase transition but with a different type of universality class. In this presentation, we discuss a measurement-only analog of the 1D XY model, in which nearest-neighbor XX and YY measurements are performed with probabilities p and 1-p respectively. By performing a Jordan-Wigner transformation, we show that this model leads to two decoupled Majorana wires with free-fermion dynamics. The critical point has an emergent U(1) spin rotational symmetry. We further perturb this model by including single-site Z measurements, which map to local inter-wire couplings in the bipartite system. The phase diagram and the scaling of mutual information and negativity are generated numerically, and connections to classical loop models are discussed. |
Friday, March 10, 2023 9:00AM - 9:12AM |
Y33.00006: Entanglement and operator dynamics in unitary circuits with generic symmetries. Akash Vijay, Laimei Nie, Xiao-Qi Sun
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Friday, March 10, 2023 9:12AM - 9:24AM |
Y33.00007: Scrambling Transition in a Radiative Random Unitary Circuit Zack Weinstein, Shane P Kelly, Jamir Marino, Ehud Altman While states and observables in generic isolated many-body systems are expected to grow in complexity indefinitely, interactions with external degrees of freedom can dramatically modify the system's dynamics. To determine whether sharp thresholds in the flow of quantum information can exist in systems with loss processes, we study quantum information scrambling in a random unitary circuit that exchanges qubits with an environment. As a result, initially localized quantum information not only spreads within the system, but spills into the environment. Using the out-of-time-order correlator (OTOC) to characterize scrambling, we find a phase transition in the directed percolation universality class at a critical swap rate: below the threshold the average OTOC exhibits ballistic growth with a tunable light cone velocity, while above it the OTOC fails to percolate within the system and vanishes uniformly after a finite time, indicating that all local operators are rapidly swapped into the environment. The transition additionally manifests in the ability to decode the system's initial quantum information from the swapped-out qubits: we present a simple decoding scheme which recovers the system's initial information with perfect fidelity in the nonpercolating phase and with continuously decreasing fidelity with decreasing swap rate in the percolating phase. |
Friday, March 10, 2023 9:24AM - 9:36AM |
Y33.00008: Transport and entanglement growth in long-range random Clifford circuits Jonas Richter, Arijeet Pal, Oliver Lunt Conservation laws and hydrodynamic transport can constrain entanglement dynamics in isolated quantum systems, manifest in a slowdown of higher Renyi entropies. Here, we introduce a class of long-range random Clifford circuits with U(1) symmetry, which act as minimal models for more generic quantum systems and provide an ideal framework to explore this phenomenon. Depending on the exponent α controlling the probability ∼r-α of gates spanning a distance r, transport in such circuits varies from diffusive to superdiffusive with a corresponding dynamical transport exponent z. We unveil that the different hydrodynamic regimes reflect themselves in the asymptotic entanglement growth according to S(t) ∼ t1/z, where the value of z depends on α. We explain this finding in terms of the inhibited operator spreading in U(1)-symmetric Clifford circuits, where the emerging light cones are intimately related to the transport behavior and are significantly narrower compared to circuits without conservation law. For sufficiently small α, we show that the presence of hydrodynamic modes becomes irrelevant such that S(t) behaves similarly in circuits with and without conservation law. |
Friday, March 10, 2023 9:36AM - 9:48AM |
Y33.00009: Interlayer electron-hole friction in tunable twisted bilayer graphene semimetal Denis A Bandurin, Alessandro Principi, Isabelle Y Phinney, Takashi Taniguchi, Kenji Watanabe, Pablo Jarillo-Herrero Charge-neutral conducting systems represent a class of materials with unusual properties governed by electron-hole (e-h) interactions. Depending on the quasiparticles' statistics, band structure, and device geometry these semimetallic phases of matter can feature unconventional responses to external fields that often defy simple interpretations in terms of single-particle physics. In this talk, we will show that small-angle twisted bilayer graphene (SA-TBG) offers a highly-tunable system in which to explore interactions-limited electron conduction. We will see that by employing a dual-gated device architecture one can tune SA-TBG devices from a non-degenerate charge-neutral Dirac fluid to a compensated two-component e-h Fermi liquid where spatially separated electrons and holes experience strong mutual friction [1]. This friction is revealed through the T2 resistivity that accurately follows the e-h drag theory we developed. Our results provide a textbook illustration of a smooth transition between different interaction-limited transport regimes and clarify the conduction mechanisms in charge-neutral SA-TBG. |
Friday, March 10, 2023 9:48AM - 10:00AM |
Y33.00010: Computational and Experimental Tools for Bloch Surface Wave Simulation and Application William M Robertson, David C Heson, Jack Liu This talk presents newly developed computational and experimental tools to explore Bloch surface wave phenomena. Bloch surface waves in nanoscale multilayer structures have significant potential in a variety of applications. The narrow resonance makes the excitation appealing for sensing and results in high surface electromagnetic field enhancement enabling surface non-linear optical effects. Additionally, the long propagation length is of value in integrated optics. Here we describe a recently developed suite of open-source computational design tools written in python and detail a compact, inexpensive experimental prism configuration using a laser diode and CMOS camera mounted in a 3D printed enclosure. The optical multilayer simulation module, available as an open-source download via the package installer for python (pip install optical_multilayer), contains a variety of functions to calculate the transmission, reflection, and cross-sectional field profile of multilayer structures containing dielectric or metal layers. The experimental platform uses simple optics and a low-cost diode laser and CMOS camera to create an effective sensing system capable of refractive index and antibody-antigen sensing. |
Friday, March 10, 2023 10:00AM - 10:12AM |
Y33.00011: Reaching the Bound for Quantum Information Scrambling of Reactions Chenghao Zhang, Sohang Kundu, Nancy Makri, Martin Gruebele, Peter G Wolynes Bounds such as the one discovered by Herzfeld [1] for quantum scrambling of atoms or by Maldacena [2] for many-body quantum chaos set an upper limit proportional to kT/h on the growth of Lyapunov exponents. We recently used out-of-time-order correlator (OTOC) time derivatives, quantum analogs of Lyapunov exponents in the limit of classical chaos, to show that this bound is not exceeded by quantum vibrational energy flow in molecules [3]. Here we explore quantum information scrambling in isomerization reactions modeled by an adiabatic double well either alone, bilinearly coupled to an oscillator, or bilinearly coupled to a harmonic bath. The scrambling rate is related to dynamics near saddle points in the activated dynamics regime at high temperature. This rate drastically decreases at low temperature, signal the onset of a regime the reaction takes places by tunneling, consistent with the bound on scrambling rate. We also study the effect of friction on scrambling rates in isomerization reactions by numerical and analytical treatments. |
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