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arXiv 2409.05971quant-ph
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近似第二定律与从量子电池中提取能量

Approximate second laws and energy extraction from quantum batteries

Debarupa Saha, Aparajita Bhattacharyya, Ujjwal Sen

AI总结:

本文定义受扰强度为 ε 的近似热操作 TO_ε,推导相应状态变换条件即近似第二定律,并证明其允许对角元与非对角元交叉耦合,从而可从量子电池提取有限 ergotropy。

摘要:

在热操作(thermal operations,TO)下,能量守恒由生成这些操作的酉算子与总哈密顿量之间的对易关系来保证。然而,在现实情形中,系统不可避免地会受到扰动或干扰,这反过来可能改变对易关系,并继而影响由 TO 支配的物理过程。我们将改变后的操作集合称为近似热操作(approximate thermal operations,TO_ε),其中 ε 表示干扰程度。我们给出了此类操作下的状态变换条件,提供了可称为近似第二定律的结果。我们表明,当系统哈密顿量中存在微弱扰动时,状态的变换会使系统状态的对角元不仅彼此发生作用,还开始与非对角元发生作用。同时,非对角元的变换也会使其开始与对角元以及其他非对角元相连接。这种交叉耦合在未受扰动的第二定律中是不允许的。作为应用,我们证明近似热操作可能从量子电池中提取有限的 ergropy(可提取功),而这是精确热操作无法实现的。

英文摘要:

Conservation of energy under thermal operations, \textbf{TO}, is ensured by commutation of the unitary generating such operations with the total Hamiltonian. However in realistic scenarios, perturbations or disturbances in the system are unavoidable, which in turn may alter the commutation relation and hence in succession may affect the physical processes governed by \textbf{TO}. We call the altered set of operations as approximate thermal operations, \textbf{TO}$_ε$, where $ε$ denotes a degree of disturbance. We provide state transformation conditions under such operations, providing what can be referred to as approximate second laws. We show that in presence of feeble perturbations in the system's Hamiltonian, the states transform in such a way that diagonal elements of the system states start talking not only with each other but also with the off-diagonal elements. In parallel, the off-diagonal elements transform in a way such that they start connecting with diagonal elements and other off-diagonal elements. Such cross-talk is disallowed in the unperturbed second laws. As an application, we show that approximate thermal operations may lead to finite ergotropy extraction from quantum batteries, something that the exact ones are unable to.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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