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 Y02: Quantum Thermodynamic Processes and ProtocolsFocus
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Sponsoring Units: GSNP DQI Chair: Steve Campbell, University College Dublin Room: Room 125 |
Friday, March 10, 2023 8:00AM - 8:36AM |
Y02.00001: Universal trade-off structure between symmetry, irreversibility, and quantum coherence in quantum processes Invited Speaker: Hiroyasu Tajima Symmetry, irreversibility, and quantum coherence are foundational concepts in physics. Here, we present a universal trade-off relation that builds a bridge between these three concepts. This trade-off particularly reveals that (1) under a global symmetry, any attempt to induce local dynamics that change the conserved quantity will cause inevitable irreversibility, and (2) such irreversibility could be mitigated by quantum coherence. Our fundamental relation also admits broad applications in physics and quantum information processing. In the context of quantum thermodynamics, we derive a universal trade-off between the coherence cost of an arbitrary quantum channel and the entropy production (thermodynamic irreversibility) of the channel. We also apply our relation to the Hayden-Preskill black hole model, we rigorously show that the rate of the escape of classical/quantum information from a black hole varies significantly with and without energy conservation. This particularly shows that when the black hole is large enough, under suitable encoding, at least about $m/4$ bits of the thrown $m$ bits will be irrecoverable until 99 percent of the black hole evaporates. As an application to quantum information processing, our trade-off also unifies and extends various restrictions on measurements, quantum computation gates, and quantum error corrections imposed by symmetry, including the Wigner-Araki-Yanase theorems and the Eastin-Knill theorems. |
Friday, March 10, 2023 8:36AM - 8:48AM |
Y02.00002: Quantum Fluctuation Theorem under Continuous Measurement and Feedback Toshihiro Yada, Nobuyuki Yoshioka, Takahiro Sagawa The fluctuation theorem has been thoroughly generalized under various feedback setups in classical systems, revealing the relationship between classical information and nonequilibrium thermodynamics. In this work, we derive the quantum fluctuation theorem in an intriguing and unexplored situation, namely under continuous measurement and feedback. In order to quantify the quantum information obtained by continuous measurement, we newly introduce the operationally meaningful information measure, which we name quantum-classical-transfer (QC-transfer) entropy. QC-transfer entropy is the quantum counterpart of the transfer entropy, which is commonly used in classical time series analysis. We also show a numerical demonstration, and propose an experiment-numerics hybrid verification method of our theoretical results. Our work indicates the general relationship between quantum information flow and quantum dissipation, which can be tested experimentally with the state-of-the-art quantum technologies. |
Friday, March 10, 2023 8:48AM - 9:00AM |
Y02.00003: Weak measurement driven thermal machines based on coupled qubits Robert Czupryniak, Bibek Bhandari, Paulo A Erdman, Andrew N Jordan We study the role of weak measurement and feedback in determining the power and performance of coupled qubit-based thermal machines. We investigate the system where the qubits are connected to a detachable bath, and one is free to specify the type of measurement and feedback performed on them. We consider the effect of both discrete and continuous measurements of the system. We examine the power output when compared to a single qubit setup, and the effect of coupling and measurement strength on the performance of the machine. Finally, we specify the type of feedback for which an optimal operational condition is achieved. |
Friday, March 10, 2023 9:00AM - 9:12AM |
Y02.00004: A Thermal State Conditioned on Pointer Bases and Its Properties Akira Sone, Diogo O Soares-Pinto, Sebastian Deffner We introduce the conditional thermal state, which is a thermal state conditioned on the pointer bases, and discuss its resource-theoretic properties. We first demonstrate that a conditional thermal state is a resource state for the quantum thermometry, which could outperform the Gibbs state in the low temperature limit. Then, we show that its asymmetry plays a role as the informational contribution in upper bounding the quantum Fisher information for quantum thermometry. Focusing on the evolution governed by the time-dependent Hamiltonian, we show that there always exists a Gibbs-preserving map in the asymptotic limit with an arbitrarily small error in converting the final exact state to the conditional thermal state. Finally, we present the relation between the symmetric divergence, called quantum J-divergence, between the exact final state and the conditional thermal state, to the quantum work in the quantum system. |
Friday, March 10, 2023 9:12AM - 9:24AM |
Y02.00005: Quantum absorption refrigerator based on 3-body interaction resets qubit autonomously Aamir Mohammed Ali, Paul Jamet Suria, José Antonio Marín Guzmán, Claudia Castillo Moreno, Jeffrey M Epstein, Nicole Yunger Halpern, Simone Gasparinetti Absorption refrigerators are autonomous machines that utilize the natural flow of heat in available thermal gradients to cool objects. Here, we present the realization of a quantum absorption refrigerator based on a three-body interaction in superconducting circuits. We demonstrate its operation by cooling a transmon qubit autonomously below its residual thermal occupation. Time-domain control can modulate the refrigerators's continuous operation to reset the qubit for quantum information processing. The refrigerator is fueled by an engineered two-photon process between three qubits. Its thermal baths are realized with coupled waveguides populated with microwave photons whose spectral density is synthesized to be thermal. We find that, under optimal operating conditions, the excited-state population of a fully excited qubit reaches the steady-state value 0.05% ± 0.05% in about 1.6 μs, in agreement with theoretical simulations. Our proof-of-concept refrigerator demonstrates that quantum thermal machines can be harnessed to perform useful tasks on quantum processing units. It also initiates a path to experimental studies of quantum thermodynamics using superconducting quantum circuits coupled to propagating thermal microwave fields. |
Friday, March 10, 2023 9:24AM - 9:36AM |
Y02.00006: Activation of Strong Local Passive States with Quantum Energy Teleportation Protocols Nayeli A. Rodriguez Briones, Hemant Katiyar, Raymond Laflamme, Eduardo Martín-Martínez
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Friday, March 10, 2023 9:36AM - 9:48AM |
Y02.00007: Energy Conservation with Post-selection Spencer C Rogers, Andrew N Jordan We investigate the energy change of the measurement apparatus when a quantum system is measured. For the qubit case, we model two possible measurement implementations: a clock model with a time-independent Hamiltonian, and a Jaynes-Cummings model with a time-dependent Hamiltonian that conserves the total excitation number. We find that, in both models, the mean energy change of the measurement apparatus, conditioned on the qubit post-selection, can be much greater than the level spacing of the qubit, like an anomalous weak value. Owing to similarities to weak measurement, the expression for the clock energy shift explicitly contains the weak value of the qubit Hamiltonian. Our two models give different results, which we explain to be a consequence of the non-degenerate spectrum of the Jaynes-Cummings model. We compare our calculations in the Jaynes-Cummings model with the experimental data of [J. Stevens, et al, Phys. Rev. Lett. 129, 110601 (2022)] and find good agreement in the appropriate regime. |
Friday, March 10, 2023 9:48AM - 10:00AM |
Y02.00008: Entanglement Entropy Evolution and Random Matrices Rishabh Kumar, Eugenio Bianchi We discuss the time-evolution of the entanglement entropy in an isolated quantum system prepared in a factorized state. We focus on random-matrix Hamiltonians from the GUE ensemble, and compare the entropy of the average density matrix to the probability distribution of the entropy over the ensemble of random Hamiltonians. While the first captures correctly the saturation value of the entropy only at the leading order, the second captures also sub-leading orders, fluctuations around the average and the short time behavior of the entanglement entropy. We discuss also the relation to other random matrix ensembles, such as GOE, and to SYK Hamiltonians. |
Friday, March 10, 2023 10:00AM - 10:12AM |
Y02.00009: Thermal and quantum fluctuation effects on non-spherical nuclei: The case of spin-1 system Mulugeta Bekele In this work we investigate the collective role of thermal and quantum fluctuations on non-equilibrium thermodynamics of a quantum system, specifcally, the quantum- |
Friday, March 10, 2023 10:12AM - 10:24AM |
Y02.00010: Probing coherent quantum thermodynamics using a trapped ion GIACOMO GUARNIERI Quantum thermodynamics is aimed at grasping thermodynamic laws as they apply to thermal machines operating in the deep quantum regime, a regime in which coherences and entanglement are expected to matter. Despite substantial progress, however, it has remained difficult to develop thermal machines in which such quantum effects are observed to be of pivotal importance. In this work, we report an experimental measurement of the genuine quantum correction to the classical work fluctuation-dissipation relation (FDR). We employ a single trapped ion qubit, realizing thermalization and coherent drive via laser pulses, to implement a quantum coherent work protocol. The results from a sequence of two-time work measurements display agreement with the recently proven quantum work FDR, violating the classical FDR by more than 10.9 standard deviations. We furthermore determine that our results are incompatible with any SPAM error-induced correction to the FDR by more than 10σ. Finally, we show that the quantum correction vanishes in the high-temperature limit, again in agreement with theoretical predictions. |
Friday, March 10, 2023 10:24AM - 10:36AM |
Y02.00011: Thermalisation in non-Markovian environments Ewen Lawrence, Peter Kirton Thermodynamics tells us that a system weakly coupled to an infinite environment will reach thermal equilibrium. In the language of open quantum systems this means we expect a thermal steady state to arise. Under the Born-Markov approximations a the bath is assumed to relax instantaneously, and equations of motion can be derived to ensure thermal equilibrium is reached. However, in many realistic systems of interest these approximations no longer hold. Here we use a variety of exact numerical methods such as time evolving matrix product operators (TEMPO) and the hierarchy of pure states (HOPS) to investigate how non-Markovian environments can perturb the thermal equilibrium state of strongly interacting many-body quantum systems. |
Friday, March 10, 2023 10:36AM - 10:48AM |
Y02.00012: Characterizing Symmetry-Protected Thermal Equilibrium by Work Extraction Yosuke Mitsuhashi, Kazuya Kaneko, Takahiro Sagawa The second law of thermodynamics prohibits work extraction from thermal equilibrium, which is formulated as complete passivity in the quantum setup; a state is called completely passive if one cannot extract work from any number of copies of the state by any unitary operations. It has been established that the necessary and sufficient condition for complete passivity is being a Gibbs ensemble. In many physical situations, however, the class of possible operations is restricted by fundamental constraints such as the symmetries of a system. In this talk, we explain the concept of complete passivity under symmetry constraints. Specifically, we have proved that a quantum state is completely passive under a symmetry constraint described by a connected compact Lie group, if and only if it is a generalized Gibbs ensemble including the conserved charges associated with the symmetry. Remarkably, our result holds for noncommutative symmetry such as SU(2) symmetry, suggesting an unconventional extension of the notion of the generalized Gibbs ensemble. Furthermore, we have investigated the case where a quantum work storage is explicitly introduced, and have proved that the condition for complete passivity remains unchanged. Our result extends the notion of thermal equilibrium to symmetric systems, and would lead to flexible design principles of quantum heat engines and batteries. Moreover, our result lays the foundation for the resource theory of thermodynamics in the presence of symmetries. |
Friday, March 10, 2023 10:48AM - 11:00AM |
Y02.00013: Finite temperature quantum walk of a single particle Andrew M Osborne, Chao Yin, Andrew Lucas We study the dynamics of a single quantum particle in a d-dimensional space, generated by a local, time-independent Hamiltonian. We prove that any state projected onto low energy eigenstates must propagate slowly, with a β-dependent effective velocity that vanishes as β is taken to infinity. The β-dependence of this effective velocity matches the conjectured scaling of the analogous butterfly velocity which has been recently studied in the context of |
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