Performance of Quantum Thermodynamic Cycles

Feldmann, Tova; Palao, José P.

doi:10.1007/978-3-319-99046-0_3

Cited by 3 publications

(3 citation statements)

References 46 publications

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“…Here, a small quantum system is envisioned to be controlled by an autonomous quantum clock. This is important for any type of unitary process requiring precise timing, from small machines operating in cycles [19] to general repeating unitary processes such as circuit-based cooling models [20][21][22][23][24].…”

Section: Discussionmentioning

confidence: 99%

Autonomous Temporal Probability Concentration: Clockworks and the Second Law of Thermodynamics

Schwarzhans,

Lock,

Erker

et al. 2020

Preprint

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According to thermodynamics, the inevitable increase of entropy allows the past to be distinguished from the future. From this perspective, any clock must incorporate an irreversible process that allows this flow of entropy to be tracked. In addition, an integral part of a clock is a clockwork, that is, a system whose purpose is to temporally concentrate the irreversible events that drive this entropic flow, thereby increasing the accuracy of the resulting clock ticks compared to counting purely random equilibration events. In this article, we formalise the task of autonomous temporal probability concentration as the inherent goal of any clockwork based on thermal gradients. Within this framework, we show that a perfect clockwork can be approximated arbitrarily well by increasing its complexity. Furthermore, we combine such an idealised clockwork model, comprised of many qubits, with an irreversible decay mechanism to showcase the ultimate thermodynamic limits to the measurement of time.

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Section: Discussionmentioning

confidence: 99%

Autonomous Temporal Probability Concentration: Clockworks and the Second Law of Thermodynamics

Schwarzhans,

Lock,

Erker

et al. 2020

Preprint

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“…From that perspective, it is interesting to observe that much current work focuses on idealized cycles as introduced by, e.g., Carnot and Otto back in the 19th century; see Refs. [1][2][3][4][5][6] for reviews. But for a small (quantum or classical) system, such 19th-century-cycles seem to be based on crude assumptions: the system needs to be repeatedly (de)coupled from a bath and work extraction is modeled semi-classically via time-dependent fields.…”

mentioning

confidence: 99%

“…( 5) follows from an underlying autonomous model-instead, we assume that the time-dependent rate matrix is generated by an ideal work reservoir. This assumption also underlies the conventional analysis of thermodynamic cycles [1][2][3][4][5][6]. Then, mechanical work is identified as…”

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confidence: 99%

Autonomous implementation of thermodynamic cycles at the nanoscale

Strasberg,

Wächtler,

Schaller

2021

Preprint

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There are two paradigms to study nanoscale engines in stochastic and quantum thermodynamics. Autonomous models, which do not rely on any external time-dependence, and models that make use of time-dependent control fields, often combined with dividing the control protocol into idealized strokes of a thermodynamic cycle. While the latter paradigm offers theoretical simplifications, its utility in practice has been questioned due to the involved approximations. Here, we bridge the two paradigms by constructing an autonomous model, which implements a thermodynamic cycle in a certain parameter regime. This effect is made possible by self-oscillations, realized in our model by the well studied electron shuttling mechanism. Based on experimentally realistic values, we find that a thermodynamic cycle analysis for a single-electron working fluid is not justified, but a fewelectron working fluid could suffice to justify it. We also briefly discuss additional open challenges to autonomously implement the more studied Carnot and Otto cycles.

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