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 CCC04: V: Non-Ergodic Quantum Dynamics |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Adrian Culver, University of California, Los Angeles Room: Virtual Room 4 |
Wednesday, March 22, 2023 3:00PM - 3:12PM |
CCC04.00001: Many-body scar states in spin-1/2 fermionic lattice models. Kiryl Pakrouski It has been shown [K. Pakrouski et al., Phys. Rev. Lett. 125, 230602 (2020)] that three families of highly symmetric states are many-body scars for any spin-1/2 fermionic Hamiltonian of the form H0+OT, where T is a generator of an appropriate Lie group. One of these families consists of the well-known eta-pairing states. In addition to having the usual properties of scars, these families of states are insensitive to electromagnetic noise and have advantages for storing and processing quantum information. We show that a number of well-known coupling terms, such as the Hubbard and the Heisenberg interactions, and the Hamiltonians containing them, are of the required form and support these states as scars without fine tuning. The explicit H0+OT decomposition for a number of most commonly used models, including topological ones, is provided. To facilitate possible experimental implementations, we discuss the conditions for the low-energy subspace of these models to be comprised solely of scars. Further, we write all the generators T that can be used as building blocks for designing new models with scars, most interestingly including the spin-orbit coupled hopping and superconducting pairing terms. We expand this framework to the non-Hermitian open systems and demonstrate that for them the scar subspace continues to undergo coherent time evolution and exhibit the “revivals.” We explicitly illustrate the novel properties of the invariant scars in a numerical study of an extended 2D tJU model. Based on [Phys. Rev. Research 3, 043156 (2021)]. |
Wednesday, March 22, 2023 3:12PM - 3:24PM |
CCC04.00002: Dephasing and Decorrelation of Spins in a Disordered Environment Subroto Mukerjee, Shreyas Raman Dephasing of spins is a major roadblock to scaling up the size of quantum computing systems. We explore the possibility of utilizing highly disordered environments which are in the Many-Body Localized phase to arrest this dephasing. We embedded 2 `special' spins in such a highly disordered environment of Heisenberg spins to act as the target qubits and use the long-time value of the spin-spin correlator ⟨σ? i⋅σ? j⟩ as an order parameter to quantify the transition between the thermal and MBL phases of this system. It is seen that the dephasing between spins, as encoded in this correlator, is impeded in a disordered environment when the system is fully localized. The order parameter yields a critical exponent, to characterize the transition between the thermal and MBL phases, that appears to be robust to changes in microscopic parameters of the system or the choice of pair of spins. |
Wednesday, March 22, 2023 3:24PM - 3:36PM |
CCC04.00003: Integrability and quench dynamics of the spin-1 Central Spin Model Long Hin Tang Central spin models provide idealized models of interactions between a central degree of freedom and a mesoscopic environment of surrounding spins. We show that the family of models with a spin-1 degree of freedom at the center and XX interactions of arbitrary strength with surrounding spins is integrable. Specifically, we derive an extensive set of conserved quantities, and obtain the exact eigenstates using the Bethe ansatz. As in the homogenous limit, the states divide into two exponentially large classes: emph{bright} states, in which the spin-1 is entangled with its surroundings, and emph{dark} states, in which it is not. The bright states further break up into two classes on resonance; these classes prevent the central spin from equilibrating on quenching to resonance. In the single spin-flip sector, analytical computations of real-time dynamics are feasible using the explicit form of the Bethe states. |
Wednesday, March 22, 2023 3:36PM - 3:48PM |
CCC04.00004: Universality of Dynamical Localization in Periodically Driven Spin Systems: From Simple Quantum Magnets to Disordered and Long-Range Models Analabha Roy Dynamical localization is one of the most startling manifestations of quantum interference, where the expected infinite temperature thermalization of a periodically driven quantum system is prevented by infinite hysteresis. The basic idea is that a driven system gets frozen when its instantaneous relaxation rate falls below the driving rate. The system is said to be "Dynamically Localized" at that state. Freezing can be seen as a many body generalization of Coherent Destruction of Tunneling (CDT), where single particle quantum systems can be localized in space as the ratio of the drive frequency and amplitude tends to certain specific values (the freezing condition). |
Wednesday, March 22, 2023 3:48PM - 4:00PM |
CCC04.00005: Discrete time crystal enabled by Stark many-body localization shuo liu, Shixin Zhang, Chang-Yu Hsieh, Shengyu Zhang, Hong Yao Discrete time crystal (DTC) has recently attracted increasing attention, but most DTC models and their properties are only revealed after disorder average. In this Letter, we propose a simple disorder-free periodically driven model that exhibits nontrivial DTC order stabilized by Stark many-body localization (MBL). We demonstrate the existence of DTC phase by analytical analysis from perturbation theory and convincing numerical evidence from observable dynamics. The new DTC model paves a new promising way for further experiments and deepens our understanding of DTC. Since the DTC order doesn't require special quantum state preparation and the strong disorder average, it can be naturally realized on the noisy intermediate-scale quantum (NISQ) hardware with much fewer resources and repetitions. Moreover, besides the robust subharmonic response, there are other novel robust beating oscillations in Stark-MBL DTC phase which are absent in random or quasi-periodic MBL DTC. |
Wednesday, March 22, 2023 4:00PM - 4:12PM |
CCC04.00006: Extracting Quantum Many-body Scarred Eigenstates with Matrix Product States Dong Yuan, Shun-Yao Zhang, Thomas Iadecola, Shenglong Xu, Yu Wang, Luming Duan, Dong-Ling Deng Quantum many-body scarred systems host nonthermal excited eigenstates immersed in a sea of thermal ones. In cases where exact expressions for these special eigenstates are not known, it is computationally demanding to distinguish them from their exponentially many thermal neighbors. We propose a matrix-product-state (MPS) algorithm, dubbed DMRG-S, to extract such states at system sizes far beyond the scope of exact diagonalization. Using this technique, we obtain scarred eigenstates in Rydberg-blockaded chains of up to L=80 sites and perform a finite-size scaling study to address the lingering question of the stability for the Néel state revivals in the thermodynamic limit. Our method also provides a systematic way to obtain exact MPS representations for scarred eigenstates near the target energy without a priori knowledge. In particular, we find several new scarred eigenstates with exact MPS representations in the kinetically constrained spin and clock models. In addition, the matrix product state and operator techniques enable us to characterize the information scrambling dynamics in scarred systems by computing the out-of-time-ordered correlator (OTOC) and Holevo information. |
Wednesday, March 22, 2023 4:12PM - 4:24PM |
CCC04.00007: Defect driven thermalization of magnets with scars and Hilbert space fragmentation Ronald Melendrez, Bhaskar Mukherjee, Prakash Sharma, Arijeet Pal, Hitesh J Changlani Clean isolated quantum systems, either thermalize or exhibit athermal behavior for a wide variety of initial conditions as in the case of quantum many body scars. We recently predicted the existence of scars (with a superspin structure) and Hilbert space fragmentation in a family of magnetic models with XXZ-Heisenberg interactions [Lee et al. Phys. Rev. B 101, 241111(R) (2020), Lee et al. Phys. Rev. B 103, 235133 (2021)], which have been realized in recent ultracold-atom experiments [Jepsen et al.,Nature Physics 18, 899–904 (2022)]. In this work, we study the robustness of the long-lived superspin by introducing ``defects" in the initially prepared spin texture - either by driving the system locally, misaligning the local spin orientations or by entangling spins. Using a combination of analyses based on the local density of states of the energy or Floquet spectrum and the effective Floquet Hamiltonian, and employing matrix product based TEBD simulations, we suggest ways of predicting the occurrence of athermal (or prethermal) dynamics. We identify dynamical parameter regimes and protocols that are robust to defects, and make predictions that may be of interest to future experiments. |
Wednesday, March 22, 2023 4:24PM - 4:36PM |
CCC04.00008: Localization enhancement in gain-loss non-Hermitian disordered models. Ivan M Khaymovich, Giuseppe De Tomasi Recently the interest to non-Hermitian (nH) disordered models has been revived, due to the claims of instability of a many-body localization to a coupling to a bath. |
Wednesday, March 22, 2023 4:36PM - 4:48PM |
CCC04.00009: Temperature dependence of the non-Hermitian skin effect associated with Kondo crossover Shin Kaneshiro, Robert Peters Strongly correlated systems (SCS) have many exciting phenomena, such as the Kondo effect. In the Kondo effect, the interaction between conduction electrons and localized impurities causes a characteristic change in physical quantities around the Kondo temperature. |
Wednesday, March 22, 2023 4:48PM - 5:00PM |
CCC04.00010: Coupled Semiconductor Bloch Equations for Studying Quantum Plasmas and Optical Responses of Photo-Generated Carriers in a Quantum Wire Danhong Huang By employing semiconductor Bloch equations and solving for electron (e) and hole (h) occupation functions, as well as for inter-band/intra-band quantum coherences between/within e and h minibands, it enables us to couple one-dimensional (1D) pulse-propagation simulations with quantum kinetics for e and h in a quantum wire. As a result, dynamical dipole contributions, both from optical polarization (i.e. inter-band bound-charge response) and from photo-generation and back-action effects due to net free-charge density (i.e. intra-band free-charge response), can be incorporated in our first-principles physics model. In particular, our numerical results on dynamic e and h intra-band coherences display standing-wave-like longitudinal oscillations with time at THz frequencies, which are further accompanied by coulomb-renormalization of dispersion relations (i.e. dependence on either carrier or laser wave vector) with respect to both plasmon modes and phase velocity in laser-pulse propagation. Such a theoretical approach facilitates to predict accurately the full transient optoelectronic response of 1D semiconductor devices during and after exposure to a resonant ultrashort laser pulse. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700