Energetics of correlations in interacting systems

Friis, Nicolai; Huber, Marcus; Perarnau-Llobet, Martí

doi:10.1103/physreve.93.042135

Cited by 35 publications

(36 citation statements)

References 51 publications

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“…Interestingly, it allows for better cooling than the case where no correlations are present. This is in agreement with recent work that has shown that correlations can play a role in work extraction and entropy flows in cooling protocols [22][23][24][25][26][27][28][29].…”

Section: Introductionsupporting

confidence: 93%

Heat-bath algorithmic cooling with correlated qubit-environment interactions

Rodríguez-Briones

Peng

et al. 2017

New J. Phys.

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Cooling techniques are essential to understand fundamental thermodynamic questions of the lowenergy states of physical systems, furthermore they are at the core of practical applications of quantum information science. In quantum computing, this controlled preparation of highly pure quantum states is required from the state initialization of most quantum algorithms to a reliable supply of ancilla qubits that satisfy the fault-tolerance threshold for quantum error correction. Heat-bath algorithmic cooling has been shown to purify qubits by controlled redistribution of entropy and multiple contact with a bath, not only for ensemble implementations but also for technologies with strong but imperfect measurements. In this paper, we show that correlated relaxation processes between the system and environment during rethermalization when we reset hot ancilla qubits, can be exploited to enhance purification. We show that a long standing upper bound on the limits of algorithmic cooling Schulman et al (2005 Phys. Rev. Lett. 94, 120501) can be broken by exploiting these correlations. We introduce a new tool for cooling algorithms, which we call 'state-reset', obtained when the coupling to the environment is generalized from individual-qubits relaxation to correlated-qubit relaxation. Furthermore, we present explicit improved cooling algorithms which lead to an increase of purity beyond all the previous work, and relate our results to the Nuclear Overhauser Effect.

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Section: Introductionsupporting

confidence: 93%

Heat-bath algorithmic cooling with correlated qubit-environment interactions

Rodríguez-Briones

Peng

et al. 2017

New J. Phys.

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“…(10) This results in the impossibility to extract energy from locally thermal states of non interacting systems, while this is possible for interacting systems. This has motivated the study of the energetics of correlations in interacting systems [45].…”

Section: Results For Locally Thermal Statesmentioning

confidence: 99%

Work extraction and energy storage in the Dicke model

2016

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We study work extraction from the Dicke model achieved using simple unitary cyclic transformations keeping into account both a non optimal unitary protocol, and the energetic cost of creating the initial state. By analyzing the role of entanglement, we find that highly entangled states can be inefficient for energy storage when considering the energetic cost of creating the state. Such surprising result holds notwithstanding the fact that the criticality of the model at hand can sensibly improve the extraction of work. While showing the advantages of using a many-body system for work extraction, our results demonstrate that entanglement is not necessarily advantageous for energy storage purposes, when non optimal processes are considered. Our work shows the importance of better understanding the complex interconnections between non-equilibrium thermodynamics of quantum systems and correlations among their subparts.

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“…To formulate our ideas we adopt a commonplace view in quantum thermodynamics, namely, that work is a central resource that is required to move systems away from freely available thermal equilibrium states [24]-an approach that has staged a diverse range of investigations within the broader field [25][26][27]. In this paradigm, previous research has investigated the work-cost (or gain) of quantum processes [28][29][30][31][32], refrigeration [33,34], or for establishing correlations [35][36][37][38].…”

Section: Tpm Schemementioning

confidence: 99%

Work estimation and work fluctuations in the presence of non-ideal measurements

et al. 2019

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From the perspective of quantum thermodynamics, realisable measurements cost work and result in measurement devices that are not perfectly correlated with the measured systems. We investigate the consequences for the estimation of work in non-equilibrium processes and for the fundamental structure of the work fluctuations when one assumes that the measurements are non-ideal. We show that obtaining work estimates and their statistical moments at finite work cost implies an imperfection of the estimates themselves: more accurate estimates incur higher costs. Our results provide a qualitative relation between the cost of obtaining information about work and the trustworthiness of this information. Moreover, we show that Jarzynski's equality can be maintained exactly at the expense of a correction that depends only on the system's energy scale, while the more general fluctuation relation due to Crooks no longer holds when the cost of the work estimation procedure is finite. We show that precise links between dissipation and irreversibility can be extended to the non-ideal situation.

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Energetics of correlations in interacting systems

Cited by 35 publications

References 51 publications

Heat-bath algorithmic cooling with correlated qubit-environment interactions

Heat-bath algorithmic cooling with correlated qubit-environment interactions

Work extraction and energy storage in the Dicke model

Work estimation and work fluctuations in the presence of non-ideal measurements

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