The Second Law and Beyond in Microscopic Quantum Setups

Uzdin, Raam

doi:10.1007/978-3-319-99046-0_28

Cited by 6 publications

(4 citation statements)

References 66 publications

(148 reference statements)

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“…Our results also find application in the context of "exotic heat machines" [37], specifically those whose aim is to generate energy coherence from thermal resources. By identifying R with the state of the machine, Theorem 2 implies that coherence cannot be created in initially incoherent systems while maintaining the machine (but not necessarily the thermal bath) in a fixed point.…”

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confidence: 73%

Coherence and Asymmetry Cannot be Broadcast

Lostaglio

Müller

2019

Phys. Rev. Lett.

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In the presence of conservation laws, superpositions of eigenstates of the corresponding conserved quantities cannot be generated by quantum dynamics. Thus, any such coherence represents a potentially valuable resource of asymmetry, which can be used, for example, to enhance the precision of quantum metrology or to enable state transitions in quantum thermodynamics. Here we ask if such superpositions, already present in a reference system, can be broadcast to other systems, thereby distributing asymmetry indefinitely at the expense of creating correlations. We prove a no-go theorem showing that this is forbidden by quantum mechanics in every finite-dimensional system. In doing so we also answer some open questions in the quantum information literature concerning the sharing of timing information of a clock and the possibility of catalysis in quantum thermodynamics. We also prove that even weaker forms of broadcasting, of whichÅberg's 'catalytic coherence' is a particular example, can only occur in the presence of infinite-dimensional reference systems. Our results set fundamental limits to the creation and manipulation of quantum coherence and shed light on the possibilities and limitations of quantum reference frames to act catalytically without being degraded. arXiv:1812.08214v2 [quant-ph]

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confidence: 73%

Coherence and Asymmetry Cannot be Broadcast

Lostaglio

Müller

2019

Phys. Rev. Lett.

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“…2. In recent years, there have been many controversies regarding the GKLS equation [49][50][51][52], particularly when solving a specific system that may violate the second law of thermodynamics [49,51,[53][54][55]. Therefore, we first calculated the average entropy production of all nine cases in the orthogonal test to verify the applicability of the GKLS equation.…”

Section: Validation Of the Calculationsmentioning

confidence: 99%

Continuous three-level quantum heat engine with high performance under medium temperature difference

Deng

Shao

Liu

et al. 2023

Journal of Applied Physics

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The possibility of utilizing quantum effects to enhance the performance of quantum heat engines has been an active topic of research, but how to enhance the performance by optimizing the engine parameters needs to be further studied. In this study, the temperature difference and dissipation modes affecting the performance of a three-level quantum heat engine were analyzed using an orthogonal test. The results indicated that the dissipation mode dominated the performance of the quantum heat engine. The quantum heat engine performs best when there is only resonance and no detuning; however, when detuning exists, a lower resonance can improve the efficiency by reducing energy losses. Regarding the temperature difference, the best performance was achieved at a medium temperature difference owing to the decreasing heat leakage. Finally, the “quantum friction” caused by the detuning could make the maximal efficiency lower than the Carnot efficiency.

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“…In this section we derive the bound on the entropy change of a quantum system that is in contact with a (thermal or non-thermal) bath [33] based on our above analysis [58]. A tight estimate of entropy change is required to deduce the maximum work obtainable from cyclic quantum machines.…”

Section: Reversibility and Entropy Productionmentioning

confidence: 99%

Thermodynamic Principles and Implementations of Quantum Machines

Ghosh

Niedenzu

Mukherjee

et al. 2018

Fundamental Theories of Physics

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The efficiency of cyclic heat engines is limited by the Carnot bound. This bound follows from the second law of thermodynamics and is attained by engines that operate between two thermal baths under the reversibility condition whereby the total entropy does not increase. By contrast, the efficiency of engines powered by quantum non-thermal baths has been claimed to surpass the thermodynamic Carnot bound. The key to understanding the performance of such engines is a proper division of the energy supplied by the bath to the system into heat and work, depending on the associated change in the system entropy and ergotropy. Due to their hybrid character, the efficiency bound for quantum engines powered by a non-thermal bath does not solely follow from the laws of thermodynamics. Hence, the thermodynamic Carnot bound is inapplicable to such hybrid engines. Yet, they do not violate the principles of thermodynamics.An alternative means of boosting machine performance is the concept of heat-to-work conversion catalysis by quantum non-linear (squeezed) pumping of the piston mode. This enhancement is due to the increased ability of the squeezed piston to store ergotropy. Since the catalyzed machine is fueled by thermal baths, it adheres to the Carnot bound.We conclude by arguing that it is not quantumness per se that improves the machine performance, but rather the properties of the baths, the working fluid and the piston that boost the ergotropy and minimize the wasted heat in both the input and the output. CONTENTS VI. Catalysis of heat-to-work conversion in quantum machines13 Model of catalyzed quantum heat engine 13 Model analysis: Derivation of the Lindblad master equation 14 Work extraction under non-linear pumping 15 Efficiency boost 16 VII. Discussion: quantumness and engine performance 17 References 17 *

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The Second Law and Beyond in Microscopic Quantum Setups

Cited by 6 publications

References 66 publications

Coherence and Asymmetry Cannot be Broadcast

Coherence and Asymmetry Cannot be Broadcast

Continuous three-level quantum heat engine with high performance under medium temperature difference

Thermodynamic Principles and Implementations of Quantum Machines

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