Work extraction from quantum systems with bounded fluctuations in work

Richens, Jonathan G.; Masanes, Lluís

doi:10.1038/ncomms13511

Cited by 34 publications

(54 citation statements)

References 21 publications

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“…In [32,33], the work statistics in the scenario of a random quantum quench are computed, and it is shown that the knowledge of the work statistics in this setting yields information on the Loschmidt echo dynamics. The importance of work fluctuations in quantum thermodynamics in a different setting than ours was also studied in [34]. In this paper, we set out to study the scenario in which one gives the Hamiltonian H(t) for a specific model then it randomizes it by rotations.…”

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confidence: 89%

Random quantum batteries

Caravelli

Wit

García-Pintos

et al. 2020

Phys. Rev. Research

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Quantum nano-devices are fundamental systems in quantum thermodynamics that have been the subject of profound interest in recent years. Among these, quantum batteries play a very important role. In this paper we lay down a theory of random quantum batteries and provide a systematic way of computing the average work and work fluctuations in such devices by investigating their typical behavior. We show that the performance of random quantum batteries exhibits typicality and depends only on the spectral properties of the time evolving operator, the initial state and the measuring Hamiltonian. At given revival times a random quantum battery features a quantum advantage over classical random batteries. Our method is particularly apt to be used both for exactly solvable models like the Jaynes-Cummings model or in perturbation theory, e.g., systems subject to harmonic perturbations. We also study the setting of quantum adiabatic random batteries.Introduction.-Quantum batteries[1-8] are a fundamental concept in quantum thermodynamics[9-17], and they have attracted interest as part of research in nano-devices that can operate at the quantum level [18][19][20]. Tools and insights from quantum information theory have provided a natural bedrock for the description of quantum nano-devices and quantum batteries from the point of view of resource and information theory [21][22][23][24][25][26][27][29][30][31].In a closed quantum system, a battery can be modeled by a time-dependent Hamiltonian H(t) evolving from an initial H 0 to a final H 1 . The system is initialized in a state ρ and, given that the entropy of the battery is constant under unitary evolution, the work extracted is given by the difference between the initial and final energies as measured in H 0 [2].In this paper, we lay down the theory of Random Quantum Batteries (RQB). The randomness lies in the initial state ρ, the Hamitonian defining the units of the energy H 0 , and the time-evolution operator U t . We are concerned with the average work extractable by (or storable in) such a device and its fluctuations.The main results of this paper are: (i) proving a typicality result for the extracted work in a large class of time dependent quantum systems. We show that -as the dimension n of the Hilbert space becomes large -the extracted work is almost always given by the difference in energy between the initial state and the completely mixed state, amplified by a quantum efficiency factor 1 + Q/n 2 that depends solely on the distribution of the eigenvalues of the exponential of the time-dependent perturbation operator K. For Q = 0, this result can be obtained by a classical system at infinite temperature. A random quantum battery can do it with limited energy resources. A non vanishing Q is a contribution that is purely quantum and depends on the constructive interference between different eigenvalues of K. The second main result is (ii) to provide a general method to study the average extractable work and its fluctuations in perturbation theory, which is essential to ...

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confidence: 89%

Random quantum batteries

Caravelli

Wit

García-Pintos

et al. 2020

Phys. Rev. Research

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“…Recently, the problem of extracting work from a quantum system has received much attention [15,[17][18][19][20][28][29][30]. To demonstrate the advantage of the bittery, we apply it to study the work extraction problem in the single-shot regime.…”

Section: Application To Single-shot Work Extractionmentioning

confidence: 99%

“…Three work extraction schemes (or work contents) have been considered previously; however there is no general agreement on the maximum extractable work. The ε-deterministic work is the amount of deterministic work that can be extracted with failure probability ε [15,18,20,28], the ε-deterministic c-bounded work (or (ε, c)-deterministic work) is the ε-deterministic work with inherent fluctuations bounded by a given amount c [18][19][20]28], while the ε-guaranteed work is the work that is guaranteed to be exceeded with failure probability ε [29]. Following Refs.…”

Section: Application To Single-shot Work Extractionmentioning

confidence: 99%

“…However, quantum weights do not seem to fit naturally into thermal operations. Specifically, quantum weights require specifically tailored Hamiltonians, they are prepared in certain pure states instead of thermal states at temperature T, and their inclusion imposes an additional restriction on the class of allowed energy-conserving global unitaries [15,[17][18][19].…”

Section: Introductionmentioning

confidence: 99%

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Informational Work Storage in Quantum Thermodynamics

Wang

2019

Quantum Reports

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We present a critical examination of the difficulties with the quantum versions of a lifted weight that are widely used as work storage systems in quantum thermodynamics. To overcome those difficulties, we turn to the strong connections between information and thermodynamics illuminated by Szilard's engine and Landauer's principle, and consider the concept of informational work storage. This concept is in sharp contrast with the usual one of mechanical work storage underlying the idealization of a quantum weight. An informational work storage system based on maximally mixed qubits that does not act as an entropy sink and is capable of truly distinguishing work from heat is studied. Applying it to the problem of single-shot work extraction in various extraction schemes, we show that for a given system state the maximum extractable work is independent of extraction scheme, in accordance with the second law of thermodynamics.

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“…Even though the above discussion implies that work should be defined with an experimental setup in mind, fundamental limits can be obtained. The question of how much work can be extracted from a quantum state has received a lot of attention recently [35,37,42,[44][45][46][47][48][49][50][51][52][53][54][55][56][57] and lies at the heart of the resource theory of quantum thermodynamics [5,35,37,49,51,56,[58][59][60][61][62][63][64]. As these works consider very abstract and general settings (hence assuming essentially full control over the system) it is not clear that the fundamental bounds are relevant in an experimental setting.…”

Section: Introductionmentioning

confidence: 99%

Optimal work extraction from quantum states by photo-assisted Cooper pair tunneling

Lörch

Bruder

Brunner

et al. 2018

Quantum Sci. Technol.

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The theory of quantum thermodynamics predicts fundamental bounds on work extraction from quantum states. As these bounds are derived in a very general and abstract setting, it is unclear how relevant they are in an experimental context, where control is typically limited. Here we address this question by showing that optimal work extraction is possible for a realistic engine. The latter consists of a superconducting circuit, where a LC-resonator is coupled to a Josephson junction. The oscillator state fuels the engine, providing energy absorbed by Cooper pairs, thus producing work in the form of an electrical current against an external voltage bias. We show that this machine can extract the maximal amount of work from all Gaussian and Fock states. Furthermore, we consider work extraction from a continuously stabilized oscillator state. In both scenarios, coherence between energy eigenstates is beneficial, increasing the power output of the machine. This is possible because the phase difference across the Josephson junction provides a phase reference.

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Work extraction from quantum systems with bounded fluctuations in work

Cited by 34 publications

References 21 publications

Random quantum batteries

Random quantum batteries

Informational Work Storage in Quantum Thermodynamics

Optimal work extraction from quantum states by photo-assisted Cooper pair tunneling

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