Quantum cooling activated by coherently-controlled thermalisation

Nie, Hanlin; Feng, Tianfeng; Longden, Samuel; Vedral, Vlatko

doi:10.48550/arxiv.2201.06954

Cited by 3 publications

(4 citation statements)

References 20 publications

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“…While emphasizing the disputed role of the causal inseparability as a resource [10,[15][16][17][18] is not a goal of this work, we intend to study how the coherent activation of the maps in the QSM allows to optimize certain thermodynamic tasks. Very recent work has addressed the implications that the QSM might have for the performance of cooling cycles [19][20][21] and work-extraction games [22]. In particular, when dealing with work extraction and heat dissipation resulting from quantum processes, a ention should be paid to the role played by quantum coherence present or created in the state of the work medium [23,24], which are crucial.…”

Section: Introductionmentioning

confidence: 99%

Work extraction from coherently activated maps via quantum switch

et al. 2022

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We characterize the impact that the application of two maps in a quantum-controlled order has on the process of work extraction via unitary cycles and its optimization. e control is based on the quantum switch model that applies maps in an order not necessarily compatible with the underlying causal structure and, in principle, can be implemented experimentally. First, we show that the activation of quantum maps through the quantum switch model always entails a non-negative gain in ergotropy compared to their consecutive application. We also establish a condition that the maps should ful ll in order to achieve a non-zero ergotropic gain. We then perform a thorough analysis of maps applied to a two-level system and provide general conditions for achieving a positive gain on the incoherent part of ergotropy. Our results are illustrated with several examples and applied to qubit and 𝑑-dimensional quantum systems. In particular, we demonstrate that a non-zero work can be extracted from a system thermalized by two coherently controlled reservoirs.

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Section: Introductionmentioning

confidence: 99%

Work extraction from coherently activated maps via quantum switch

et al. 2022

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“…Compared with operations occurring in a well-de ned order, the advent of quantum SWITCH has o ered advantages in a plethora of information processing tasks like channel discrimination [4], computation [5], classical and quantum communication [6][7][8][9], and others. In a similar spirit, the relevance of the quantum SWITCH in the domain of quantum thermodynamics has recently been observed in the framework of quantum cooling [10][11][12][13], boosted quantum battery charging [14], and thermodynamic work extraction games [15,16]. As regards the latter, quantum SWITCH of two thermal maps has been considered for extraction of the free energy amount of work from thermal states [15] as well as with respect to work extraction under a unitary cyclic evolution of a quantum system [16].…”

Section: Introductionmentioning

confidence: 94%

Activation of thermal states by quantum SWITCH-driven thermalization and its limits

Guha¹,

Roy²,

Simonov³

et al. 2022

Preprint

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Coherently controlled thermalization via the quantum SWITCH allows to activate the state of a work medium and, hence, extract a non-zero work. However, such thermalization puts certain constraints on extractable work with respect to the temperatures of the work medium and reservoirs. We analyze these constraints and the possible ways to go beyond them. We characterize the impact that entanglement between target and control has on ergotropy and highlight the role of the coherence present in the state of the work medium. Last but not least, some of the results are generalized to the case of 𝑁 -switch.

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“…ICO has been demonstrated in a number of groundbreaking experiments [49][50][51][52][53][54][55][56][57], many of which rely on a device known as a quantum switch to enable superpositions of the order in which unitary operations are applied to a system. Perhaps even more importantly, ICO provides a new approach to thinking about old problems and can inspire simpler solutions with definite causal order that take advantage of coherent superpositions of operations to achieve the same goals [58][59][60]. This is a powerful new tool that is only beginning to be understood so, while it is remarkable to find yet another important application for coherent superpositions of unitaries, it would not be surprising to discover that coherent-superposition protocols have many more varied applications that we are only beginning to fathom.…”

Section: Introductionmentioning

confidence: 99%

“…Coherent superpositions have already been studied in the context of cooling through ICO [47,59,61], where quantum states can be serially cooled through subsequent applications of an ICO-cooling procedure. In contrast, our method achieves the ultimate cooling limit, that of pure states, by combining standard HBAC with a single coherent superposition step.…”

Section: Introductionmentioning

confidence: 99%

Breaking the limits of purification: postselection enhances heat-bath algorithmic cooling

Goldberg

Heshami

2023

J. Phys. Commun.

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Quantum technologies require pure states, which are often generated by extreme refrigeration. Heat-bath algorithmic cooling is the theoretically optimal refrigeration technique: it shuttles entropy from a multiparticle system to a thermal bath, thereby generating a quantum state with a high degree of purity. Here, we show how to surpass this hitherto-optimal technique by taking advantage of a single binary-outcome measurement. Our protocols can create arbitrary numbers of pure quantum states without any residual mixedness by using a recently discovered device known as a quantum switch to put two operations in superposition, with postselection certifying the complete purification.

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Quantum cooling activated by coherently-controlled thermalisation

Cited by 3 publications

References 20 publications

Work extraction from coherently activated maps via quantum switch

Work extraction from coherently activated maps via quantum switch

Activation of thermal states by quantum SWITCH-driven thermalization and its limits

Breaking the limits of purification: postselection enhances heat-bath algorithmic cooling

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