Quantum thermal absorption machines: refrigerators, engines and clocks

Mitchison, Mark T.

doi:10.1080/00107514.2019.1631555

Cited by 149 publications

(109 citation statements)

References 178 publications

(279 reference statements)

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“…For simplicity, the theory was only applied to the free field case [38], in order to demonstrate the technicalities associated with coupling a different NHC thermostat [44,45] to each field mode. However, this theory is intended for situations where the field is coupled to a spin system [47][48][49][50][51][52][53][54][55][56][57]. In this case, the use of NHC thermostats in the dynamics of the thermal state of the field would make it possible to simulate processes that, to our knowledge, have not been investigated so far.…”

Section: Discussionmentioning

confidence: 99%

Proposal of a Computational Approach for Simulating Thermal Bosonic Fields in Phase Space

Sergi

Grimaudo

Hanna

et al. 2019

Physics

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When a quantum field is in contact with a thermal bath, the vacuum state of the field may be generalized to a thermal vacuum state, which takes into account the thermal noise. In thermo field dynamics, this is realized by doubling the dimensionality of the Fock space of the system. Interestingly, the representation of thermal noise by means of an augmented space is also found in a distinctly different approach based on the Wigner transform of both the field operators and density matrix, which we pursue here. Specifically, the thermal noise is introduced by augmenting the classical-like Wigner phase space by means of Nosé-Hoover chain thermostats, which can be readily simulated on a computer. In this paper, we illustrate how this may be achieved and discuss how non-equilibrium quantum thermal distributions of the field modes can be numerically simulated.Published in Physics 2019, 1(3), 402-411; https://doi.org/10.3390/physics1030029 I. INTRODUCTIONAccording to quantum field theory, the vacuum is filled by fluctuating quantum fields.Such fields are present both in condensed matter systems [1-6] and, more generally, in empty space-time, where their existence is believed to be linked to dark matter and dark energy [7][8][9][10][11][12][13][14][15][16]. Universal phenomena such as the emergence of order, symmetry breaking, and phase transitions are related to the thermal degrees of freedom the first time in order to stress that we are not using the expression in a literal meaning. of the fields [17,18]. Hence, the study of the thermal excitation of the quantum vacuum is of interest to many research areas [19][20][21][22][23]. In thermo field dynamics [24][25][26], the vacuum state is generalized to a thermal vacuum state by doubling the dimension of the Fock space of the original vacuum. The additional dimension of the Fock space represent the degrees of freedom of the thermal bath, which are involved in the excitation and de-excitation processes of the thermal system.In this paper, we illustrate an approach to simulate the thermal distributions of bosonic * Electronic address: asergi@unime.it † Electronic address: roberto.grimaudo01@unipa.it ‡ Electronic address: gabriel.hanna@ualberta.ca § Electronic address: antonino.messina@unipa.it H (Q,P ) = J ω JP 2 J 2λ 2 J + ω J λ 2 JQ 2 J the Wigner transform of the field Hamiltonian in Equation (1) reads: H (Q,P ) = J P 2 J 2µ J + µ J ω 2 J Q 2 J 2 = J

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Section: Discussionmentioning

confidence: 99%

Proposal of a Computational Approach for Simulating Thermal Bosonic Fields in Phase Space

Sergi

Grimaudo

Hanna

et al. 2019

Physics

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“…Scientific activity in the area of thermal machines has been boosted in recent years by the increasing importance that society is placing on sustainable energy. The inevitable tendency towards miniaturization and the importance of recycling waste heat provide strong motivations to consider microscopic thermal machines, for which quantum effects can become relevant [1,2] and may even be exploited (see, for example, Refs. [3][4][5][6][7][8][9][10]).…”

Section: Introductionmentioning

confidence: 99%

Quasiperiodic quantum heat engines with a mobility edge

Cecilia

Mitchison

Purkayastha

et al. 2020

Phys. Rev. Research

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Steady-state thermoelectric machines convert heat into work by driving a thermally generated charge current against a voltage gradient. In this work, we propose a new class of steady-state heat engines operating in the quantum regime, where a quasiperiodic tight-binding model that features a mobility edge forms the working medium. In particular, we focus on a generalization of the paradigmatic Aubry-André-Harper (AAH) model, known to display a single-particle mobility edge that separates the energy spectrum into regions of completely delocalized and localized eigenstates. Remarkably, these two regions can be exploited in the context of steadystate heat engines as they correspond to ballistic and insulating transport regimes. This model also presents the advantage that the position of the mobility edge can be controlled via a single parameter in the Hamiltonian. We exploit this highly tunable energy filter, along with the peculiar spectral structure of quasiperiodic systems, to demonstrate large thermoelectric effects, exceeding existing predictions by several orders of magnitude. This opens the route to a new class of highly efficient and versatile quasiperiodic steady-state heat engines, with a possible implementation using ultracold neutral atoms in bichromatic optical lattices. arXiv:1908.05139v2 [cond-mat.dis-nn]

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“…The ideal QAR based on two-body interaction can saturate the Carnot bound, at the cost of vanishing cooling power [6]. A more practical bound for QAR then can be efficiency at maximum cooling power * [31].…”

Section: Introductionmentioning

confidence: 99%

Two-body quantum absorption refrigerators with optomechanical-like interactions

Naseem¹,

Misra²,

Müstecaplıoğlu³

2020

Quantum Sci. Technol.

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Quantum absorption refrigerator (QAR) autonomously extracts heat from a cold bath and dumps into a hot bath by exploiting the input heat from a higher temperature reservoir. QARs typically require three-body interactions. We propose and examine a two-body QAR model based upon optomechanical-like coupling in the working medium composed of either two two-level systems or two harmonic oscillators or one two-level atom and a harmonic oscillator. In the ideal case without internal dissipation, within the experimentally realizable parameters, our model can attain the coefficient of performance that is arbitrarily close to the Carnot bound. We study the efficiency at maximum power, a bound for practical purposes, and show that by using suitable reservoir engineering and exploiting the nonlinear optomechanial-like coupling, one can achieve efficiency at maximum power close to the Carnot bound, though the power gradually approaches to zero as the effeciency approaches the Carnot bound. Moreover, we discuss the impact of non-classical correlations and the size of Hilbert space on the cooling power. Finally, we consider a more realistic version of our model in which we consider heat leaks that makes QAR non-ideal and prevent it to achieve the Carnot efficiency.

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Quantum thermal absorption machines: refrigerators, engines and clocks

Cited by 149 publications

References 178 publications

Proposal of a Computational Approach for Simulating Thermal Bosonic Fields in Phase Space

Proposal of a Computational Approach for Simulating Thermal Bosonic Fields in Phase Space

Quasiperiodic quantum heat engines with a mobility edge

Two-body quantum absorption refrigerators with optomechanical-like interactions

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