Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session D09: Quantum ThermodynamicsFocus
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Sponsoring Units: DQI Chair: Ruichao Ma, Purdue University Room: 106 |
Monday, March 2, 2020 2:30PM - 2:42PM |
D09.00001: Analyzing the efficacy and work extraction of a quantum Maxwell’s demon Xingrui Song, Mahdi Naghiloo, Kater Murch In a quantum Maxwell’s demon experiment, two major quantities are commonly investigated - the average work extraction〈W〉, and the efficacy γ which measures the violation of Jarzynski’s equality when extracted information and feedback is not accounted for. Here, we carefully analyze the relation between these two quantities, and find that they are not maximized simultaneously, requiring different feedback protocols. Furthermore, we investigate Maxwell’s demon protocols for higher dimensional Hilbert spaces finding even stronger violations of Jarzynski’s equality. Our study further reveals the thermodynamic implications of the exponentially large state space available in quantum systems. |
Monday, March 2, 2020 2:42PM - 2:54PM |
D09.00002: Simulating a quantum heat engine on transmon qubits Nicholas Materise, Eliot Kapit We devise a scheme to simulate a quantum heat engine using in an array of flux-tunable |
Monday, March 2, 2020 2:54PM - 3:06PM |
D09.00003: Macroscopic Thermodynamic Reversibility in Quantum Many-Body Systems Philippe Faist, Takahiro Sagawa, Kohtaro Kato, Hiroshi Nagaoka, Fernando Brandão The resource theory of thermal operations, an established model for small-scale thermodynamics, provides an extension of equilibrium thermodynamics to nonequilibrium situations. On a translation-invariant lattice with local interactions, we show that ergodic states (i.e. states that have sharp statistics for any translation-invariant observable) can be reversibly converted to and from the thermal state with thermal operations and a small amount of coherence. This proves the emergence of an operationally well-justified thermodynamic potential for this class of states, which includes states that are not in equilibrium. As an intermediate result of independent interest, we show that the gap between the min- and max-relative entropies controls the amount of coherence that is present in the state and that if this gap is small, the state can be approximately reversibly converted to and from the thermal state with a small reference frame. Our results provide a strong link between the abstract resource theory of thermodynamics and more realistic physical systems that go beyond the i.i.d. setting. |
Monday, March 2, 2020 3:06PM - 3:42PM |
D09.00004: What is Quantum Thermodynamics? Invited Speaker: Sebastian Deffner We are the verge of a technological revolution. Over the last couple of years the first computational devices have become commercially available that promise to exploit so-called quantum supremacy. Even though the thermodynamic cost for processing classical information has been known since the 1960s, the thermodynamic description of quantum computers is still at its infancy. This is due to the fact that many notions of classical thermodynamics, such as work and heat, do not readily generalize to quantum systems. In this talk, we will outline a novel conceptual framework of an emerging theory, Quantum Thermodynamics, and illustrate its applicability, mindset, and questions with a few pedagogical examples. |
Monday, March 2, 2020 3:42PM - 3:54PM |
D09.00005: Entanglement transport and thermalization in an isolated quantum spin chain Shunji Tsuchiya, Ryosuke Yoshii Entanglement transport is considered to be essential for understanding thermalization in an isolated quantum system. In this work, we study transport of entanglement entropy (EE) in the Ising model with the next-nearest-neighbor interaction as well as the transverse and longitudinal magnetic fields. We calculate EE in a spin chain which consists of a single spin at the edge (A) and the bulk part (B). We compare time-evolution of EE for two different initial settings: the one with entanglement between A and B and the other one without it. The propagation speed of EE can be estimated by the time at which the EEs starting from the two initial conditions show deviation. We find that EE propagates ballistically with a constant velocity and that the propagation speed is enhanced when thermalization occurs. We also calculate the propagation speed of EE from mutual information between A and a subsystem in B. The velocities calculated by the two different methods agree well. We will discuss the relation between propagation of EE and thermalization. |
Monday, March 2, 2020 3:54PM - 4:06PM |
D09.00006: Characterizing complexity of many-body quantum dynamics by higher-order eigenstate thermalization Kazuya Kaneko, Eiki Iyoda, Takahiro Sagawa Characterizing quantum many-body chaos has attracted renewed attention in condensed matter physics, quantum information, and high-energy physics. There are two fundamental concepts regarding this problem. One is the eigenstate thermalization hypothesis (ETH) stating that individual energy eigenstates are thermal. The other is information scrambling, which is quantified by out-of-time-ordered correlators (OTOCs). We propose a higher-order generalization of the ETH, named by the k-ETH (k=1, 2,…) , which provides a unified view on the above two concepts. The lowest order ETH (1-ETH) is the conventional ETH, and the second order ETH (2-ETH) is a sufficient condition of the decay of OTOCs at late times. Our basic idea is that chaotic dynamics share common properties with random unitary dynamics even at a higher level than conventional ergodicity. The k-ETH also implies a universal behavior of the kth-Renyi entanglement entropy of individual energy eigenstates. In particular, we show that the Page correction originates from the higher-order ETH. We numerically verified that the 2-ETH approximately holds for nonintegrable systems, but does not hold for integrable systems. |
Monday, March 2, 2020 4:06PM - 4:18PM |
D09.00007: Collective phenomena in quantum thermodynamics: from mitigation to amplification of the baths' action Camille Lombard Latune, Ilya Sinayskiy, Francesco Petruccione An increasing number of papers in quantum thermodynamic have shown that collective effects can be beneficial for thermodynamic tasks. In order to understand better why and when such enhancements can happen, we analyse in details the energetic, entropic, and more generally thermodynamic consequences of collective coupling between an ensemble of identical systems (spin or atoms) and their bath. |
Monday, March 2, 2020 4:18PM - 4:30PM |
D09.00008: Thermalization of a qubit strongly interacting with a bosonic environment Patrick Orman, Dexter Grant Mitchell, Ryoichi Kawai When a quantum system is placed in a thermal environment, we assume that the system relaxes to the Gibbs state in which decoherence takes place in the system energy eigenbasis. However, when the coupling between system and environment is strong, the thermal state is not necessarily the Gibbs state, and the system density matrix does not have to be diagonal in the energy eigenbasis. The theory of einselection by Zurek suggests that decoherence takes place in the pointer basis rather than in the energy eigenbasis, which can be interpreted as continuous measurement by the environment. However, the actual matrix elements are not known. Based on the theory of environment-induced decoherence, we introduce a couple of propositions: (1) in the strong coupling limit, the Gibbs state is projected to the convex hull spanned by the pointer basis, which necessarily increases the system entropy, and (2) the transition from the Gibbs state to the pointer limit takes place along the projection line perpendicular to the convex hull. We justify these propositions by exact numerical simulation of a qubit interacting with an infinitely large bosonic environment through various coupling Hamiltonians. |
Monday, March 2, 2020 4:30PM - 4:42PM |
D09.00009: Kinetics of many-body reservoir engineering Hugo Ribeiro, Florian Marquardt Quantum simulators based on superconducting circuits can be used to study |
Monday, March 2, 2020 4:42PM - 4:54PM |
D09.00010: Topological effects in quantum thermodynamics Charles Stafford, Yiheng Xu, Ferdinand Evers The thermodynamics of open quantum systems coupled to topological fields is analyzed. Both the Aharonov-Bohm effect for systems of charged particles and the Aharonov-Casher effect for systems of neutral spin-1/2 particles are considered, and a general definition for the flux of a physical observable is proposed. A proper treatment of the work done by the topological fields is necessary to ensure that the entropy of the system is a state function, and to avoid certain thermodynamic paradoxes. In particular, the flux of entropy in the system induced by the topological fields naively appears to diverge as the temperature approaches absolute zero, in violation of the 3rd law of thermodynamics. |
Monday, March 2, 2020 4:54PM - 5:06PM |
D09.00011: Fluctuations in stored work bound the charging power of quantum batteries Luis Garcia-Pintos, Alioscia Hamma, Adolfo Del Campo We investigate the connection between the charging power of a quantum battery and the fluctuations of the work stored in it. We show that in order to have a non-zero rate of change of the extractable work, the work fluctuations must be non-zero. This is presented in terms of an uncertainty relationship that bounds the speed of the charging process of any quantum system. Our findings also identify quantum coherence in the battery as a resource in the charging process, which we illustrate on a toy model of a heat engine. |
Monday, March 2, 2020 5:06PM - 5:18PM |
D09.00012: Thermodynamics features of quantum memristors Lucas Céleri, Mikel Sanz, Enrique Solano, Gabriel Landi Quantum memristors are devices holding great promise as a platform for quantum computation, especially when considering neuromorphic quantum computation. These devices are characterized by their non-Markovian behaviour. Here we describe such devices as a kind of thermodynamic engine operated by a Maxwell demon, but, instead of work, the output of such engine is non-Markovianity (time correlations), that can be employed to power quantum computation, for instance. We are therefore able to provide a thermodynamic description of this device, thus paving the way for establishing the limits of its applicaility for information processing. |
Monday, March 2, 2020 5:18PM - 5:30PM |
D09.00013: Heat Transfer in Mesoscopic Systems Gabriel Weiderpass, Gustavo Monteiro, Amir O. Caldeira In this talk, we present an analytical solution for the heat flux along a harmonic chain connecting two identical reservoirs at different temperatures, in the stationary regime. In this model, the end points correspond to Brownian particles with different damping coefficients. This analytical expression for the heat conductance in mesoscopic chains allows for direct comparison with experiments and shed some light on the validity of the Fourier law in one-dimensional quantum systems. |
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