Bulletin of the American Physical Society
2023 APS March Meeting
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session S66: Open Quantum Systems IIFocus
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Sponsoring Units: DAMOP Chair: Guoqing Wang, Massachusetts Institute of Technology MI Room: Room 413 |
Thursday, March 9, 2023 8:00AM - 8:36AM |
S66.00001: Constructing open many-body quantum systems with atoms, cavities and light Invited Speaker: Dan M Stamper-Kurn Trapping ultracold atoms within strongly coupled optical cavities allow us to engineer rich many-body quantum systems that are essentially open. I will describe experiments in which single, few, or many ultracold atoms are placed with high spatial control within Fabry-Perot optical cavities. Our focus generally is on pushing the limits of quantum measurement, and also exerting feedback control over quantum properties of the atomic system. I will discuss three main results: high-fidelity mid-circuit measurement within an atomic tweezer array, precise detection of an atomic ensemble undergoing non-equilibrium thermodynamics, and autonomous feedback stabilization of an atomic spin system. |
Thursday, March 9, 2023 8:36AM - 8:48AM |
S66.00002: Lattice relaxation times for spin qubits in MOFs with semi-empirical spectral densities Katy Aruachan Fajardo, Yamil J Colón, Daniel D Aravena Ponce, Felipe F Herrera Understanding the mechanisms that determine relaxation times for molecular spin qubits in metal-organic framework (MOF) crystals is essential for applications in precision measurements and quantum information processing [1]. Recent spin-echo experiments on the spin relaxation of vanadyl-based qubits as a function of magnetic field and temperature has stimulated the development of phenomenological and ab-initio quantum mechanical modeling techniques [1-3]. We propose an alternative method with a semi-empirical approach for building Redfield quantum master equations based on a stochastic fluctuation model for the molecular gyromagnetic tensor due to the interaction of molecular spin impurities with crystal lattice vibrations. The spin relaxation rates are obtained from a semi-empirical bath autocorrelation function that captures the experimental temperature dependence through a fitting procedure. These model spectral densities are used for computing the spin population and decoherence dynamics of vanadyl-based spin qubits beyond cryogenic temperatures (>50 K) and high magnetic fields, where the Zeeman effect dominate the relaxation dynamics. Our results quantitatively agree with experiments [3] and represent a solid foundation for the theoretical characterization of other spin qubits in MOFs, for the rational design of novel quantum magnetometers based on this material class. |
Thursday, March 9, 2023 8:48AM - 9:00AM |
S66.00003: Lamb shift for the detection of the Unruh effect Navdeep Arya, D. Jaffino Stargen, Kinjalk Lochan, Sandeep K Goyal The Unruh effect states that a uniformly accelerated observer perceives the inertial vacuum as a thermal state at a temperature proportional to the observer's acceleration. At the accelerations achievable in laboratory settings, the thermal signature in the atom’s response is so feeble that the Unruh effect has eluded experimental detection till now. Numerous physical observables, including atomic transition rates, particle decay rates, and geometric phase, have been studied under varied settings as possible candidates for capturing a measurable and unambiguous signature of the Unruh effect. |
Thursday, March 9, 2023 9:00AM - 9:12AM Author not Attending |
S66.00004: Dissipative dynamics of an impurity with spin-orbit coupling Alberto Cappellaro Spin-orbit coupling (SOC) plays a central role in topological phases of matter. In reality, all of these topological materials are coupled to some dissipative environment, which affects the robustness of the phase. Surprisingly, SOC and dissipation are rarely considered together, which hinders our understanding of the interplay between the two phenomena. Here, we fill this gap by considering dissipative dynamics of a spin-orbit coupled particle in one dimension. |
Thursday, March 9, 2023 9:12AM - 9:24AM |
S66.00005: First order phase transition in a dissipative Bose-Hubbard chain Robbe Ceulemans Atomic condensates are attractive simulators to study quantum systems at equilibrium thanks to their highly controllable nature. In recent years, they have also become more prominent in studies on non-equilibrium physics. One way to achieve out-of-equilibrium ultracold gases is by introducing dissipation, which can be done in a controllable way. In this talk we theoretically address a Bose-Hubbard chain with losses at one site in the centre, using the Truncated Wigner approximation. We observe bimodality and critical behaviour in the non-equilibrium steady states of the dissipative site, qualitatively corresponding to experimental observations. This indicates the presence of a first order phase transition. Further, we investigate the ability of a more compact, effective description to reproduce this steady-state physics. We find that the suggested model approaches the steady states remarkably well with small deviations in its dynamical properties like the effective Liouvillian gap. The dark soliton state, observed in simulations of the dissipative Bose-Hubbard model, can also be reproduced with this effective description. |
Thursday, March 9, 2023 9:24AM - 9:36AM |
S66.00006: Limitations of a multi-Raman-pulse atom interferometry acceleration sensor Philip C Chrostoski, Scott Bisson, Daniel B Soh Given that atom interferometry has been the most successful quantum sensing application, ways to increase the sensitivity is a current topic of interest. One way to increase the sensitivity is an increase in the momentum axis by providing a larger momentum to the atom cloud. This has been done through increasing the number of central Raman π − pulses. In this approach, a longer stay in the intermediate high energy state, which is often neglected through adiabatic elimination due to large optical detuning, causes a higher chance of undesired spontaneous decay. The loss of quantum information of the atomic states due to this undesired spontaneous decay will add an additional error to the atom interferometer. In this work, we consider an open quantum system using the Lindblad master equation to devise a model for the atomic state dynamics that incorporates the undesired spontaneous decay. We formulate a noise model and combined it with the mean-value-deviation to analyze our figure of merit error in the measurement of local acceleration. Our theoretical results show the measurement error will be dominated by the inverse square noise dependence on the number of Raman pulses in low numbers of Raman pulses, while that in the high numbers of Raman pulses will be dominated by the loss of quantum information through the undesired spontaneous decay in the intermediate high energy state. |
Thursday, March 9, 2023 9:36AM - 9:48AM |
S66.00007: Why the dissipative gap fails to predict relaxation times in dissipative lattice models Gideon Lee, Alexander McDonald, Aashish A Clerk Quantum systems exhibiting effective non-Hermitian dynamics are the subject of considerable recent interest. Among their most striking features is the non-Hermitian skin effect (NHSE), where a small change in boundary conditions can completely change the spectrum and localization of eigenmodes. Recent work suggests that the NHSE directly also yields surprising dynamics: anomalously long relaxation times that are not simply given by the dissipative gap of the system's Liouvillian, but instead grow with system size and depend on the NHSE localization length ξloc. Despite the simplicity of the underlying argument, we show here that the situation is often more complex: a subtle interference effect makes the extreme localization of modes largely irrelevant in determining relaxation times. Focusing on a fully quantum open-systems implementation of the paradigmatic Hatano-Nelson model [1], we show why this intuitive interference effect must occur, how it helps determine anomalous relaxation times, and how this physics is ultimately a consequence of locality. We also show that there is a crucial sensitivity to particle statistics (i.e. fermionic versus bosonic models), and that similar effects occur in other non-Hermitian quantum lattice models. |
Thursday, March 9, 2023 9:48AM - 10:00AM |
S66.00008: First Devices with Transport Properties Outside the Onsager Relation Jochen D Mannhart According to Onsager’s reciprocal relation [1], in linear response, the probability of electron transfer through any two-terminal device must be symmetric with respect to the reversal of the current direction. All known devices obey this symmetry. |
Thursday, March 9, 2023 10:00AM - 10:12AM |
S66.00009: Matching perturbative and non-perturbative descriptions of the reorganization energy Evgeny Mozgunov, Yangheng Jizhe We revisit an old concept of reorganization energy that appears in Marcus theory and, more recently, in the flux qubit tunneling experiments. Reorganization energy can be observed in the initial-state-dependent shift of the tunneling rate peak from the zero-bias point of the flux qubit. Taking advantage of the various open system methods developed for quantitative prediction of the general evolution of flux qubits in quantum annealing, we investigate the specific setting of the tunneling experiment. We find that both perturbative and non-perturbative methods demonstrate a shift in the tunneling rate peak. Rigorous ranges of validity of those methods allow us to observe with controlled numerical precision the crossover between the Lorenzian and the Gaussian shapes of the peak, as well as the adjustments on the value of the shift. The ranges of validity overlap only for a special case of the bath, but the qualitative insights we draw are applicable for the realistic bath as well. |
Thursday, March 9, 2023 10:12AM - 10:24AM Author not Attending |
S66.00010: Pseudomode description of general open quantum systems with applications to thermodynamics Graeme Pleasance, Francesco Petruccione The pseudomode method has been recognized as a powerful tool for the description of non-Markovian open system dynamics. The technique is based on replacing a bosonic environment with a small set of damped harmonic oscillators - the pseudomodes - thereby mapping the initial system onto a simpler configuration described by a Markovian master equation. In this talk, we present an efficient mapping scheme that combines several key features of previous approaches, enabling the optimal construction of pseudomode networks representing general non-Markovian environments. For special cases involving non-Hermitian system-pseudomode interactions, we also establish general conditions under which the corresponding master equation may be converted into Gorini-Kossakowski-Sudarshan-Lindblad (GKSL) form. Finally, we demonstrate the application of our results by analyzing the performance of a quantum Otto cycle at strong system-bath coupling. |
Thursday, March 9, 2023 10:24AM - 10:36AM |
S66.00011: Controlling bright and dark periods of entanglement in dissipative interacting qubits using a radiation field Gehad K Sadiek, Rahma Abdelmagid Quantum logic gates demand a coherent controllable coupling among qubits. One of the main obstacles toward realizing a practical quantum computer is decoherence in the qubits due to their inevitable interaction with the environment. It was shown that entanglement between two non-interacting, but initially entangled, qubits may suffer sudden death, with no revival, due to coupling to pure vacuum noise (Yu and Eberly 2004 Phys. Rev. Lett. 93 140404 ). Furthermore, two interacting qubits coupled to a dissipative or dephasing environment were found to exhibit bright and dark periods of entanglement dynamics. In this work, we show how the exposure of such a dissipative coupled qubits system to a quantum radiation field would significantly affect the durations of these periods and may entirely eliminate them depending on the initial state of the system and its enclosed entanglement as well as the radiation intensity. The thermal effect of the environment on the system dynamics is explored as well. |
Thursday, March 9, 2023 10:36AM - 10:48AM |
S66.00012: Topological synchronization of quantum van der Pol oscillators Christopher W Wächtler, Gloria Platero To observe synchronization in large networks of classical or quantum systems demands both excellent control of the interactions between nodes and very accurate preparation of initial conditions due to the involved nonlinearities and dissipation. This limits its applicability for future devices. We demonstrate a route towards significantly enhancing the robustness of synchronized behavior in open nonlinear systems that utilizes the power of topology. In lattices of quantum van der Pol oscillators with topologically motivated couplings, boundary synchronization emerges in the classical mean field as well as the quantum regime. In addition to its robustness against disorder and initial state perturbations, the observed dynamics is independent of the underlying topological model provided the existence of topological zero-energy modes. Our work extends the notion of topology to the general nonlinear dynamics and open quantum system realm with applications to networks where specific nodes need special protection like power grids or quantum networks. |
Thursday, March 9, 2023 10:48AM - 11:00AM |
S66.00013: Liouvillian gap and single spin-flip dynamics in the dissipative Fermi-Hubbard model Hironobu Yoshida, Hosho Katsura Motivated by recent progress in cold-atom experiments, we analyze the SU(N) Fermi-Hubbard model on a d-dimensional hypercubic lattice with two-body loss. By focusing on states near the ferromagnetic steady states, we obtain the Liouvillian gap in closed form for any d and N. We also investigate the dynamics of a ferromagnetic initial state with a single spin flip analytically in strongly- and weakly-interacting and dissipative limits and numerically for various values of the parameters. Then we show that, by decreasing the strength of the interaction and loss, a crossover from the power-law decay to the exponential decay occurs. We expect that our findings can be tested experimentally with ultracold alkaline-earth-like atoms in an optical lattice. |
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