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We show that a cyclic unitary process can extract work from the thermodynamic equilibrium state of an engineered quantum dissipative process. Systems in the equilibrium states of these processes serve as batteries, storing energy. The…

Quantum Physics · Physics 2019-06-05 Felipe Barra

Employing currently available quantum technology, we design and implement a non-classically correlated SWAP heat engine that allows to achieve an efficiency above the standard Carnot limit. Such an engine also boosts the amount of…

Quantum Physics · Physics 2023-11-06 Marcela Herrera , John H. Reina , Irene D'Amico , Roberto M. Serra

Many studies of quantum-size heat engines assume that the dynamics of an internal system is unitary and that the extracted work is equal to the energy loss of the internal system. Both assumptions, however, should be under scrutiny. In the…

Statistical Mechanics · Physics 2017-04-05 Yohei Morikuni , Hiroyasu Tajima , Naomichi Hatano

Light can be squeezed by reducing the quantum uncertainty of the electric field for some phases. We show how to use this purely quantum effect to extract net mechanical work from radiation pressure in a simple quantum photon engine. Along…

Quantum Physics · Physics 2026-01-15 A. Tejero , D. Manzano , P. I. Hurtado

The amount of work that can be extracted from a quantum system can be increased by exploiting the information obtained from a measurement performed on a correlated ancillary system. The concept of daemonic ergotropy has been introduced to…

Quantum Physics · Physics 2023-10-31 Daniele Morrone , Matteo A. C. Rossi , Marco G. Genoni

We study the mechanical performance of quantum rotor heat engines in terms of common notions of work using two prototypical models: a mill driven by the heat flow from a hot to a cold mode, and a piston driven by the alternate heating and…

Quantum Physics · Physics 2018-05-10 Stella Seah , Stefan Nimmrichter , Valerio Scarani

There are several definitions of energy density in quantum mechanics. These yield expressions that differ locally, but all satisfy a continuity equation and integrate to the value of the expected energy of the system under consideration.…

Quantum Physics · Physics 2023-06-29 Francisco Torres Arvizu , Adrian Ortega , Hernán Larralde

The quantum ergotropy quantifies the maximal amount of work that can be extracted from a quantum state without changing its entropy. Given that the ergotropy can be expressed as the difference of quantum and classical relative entropies of…

Quantum Physics · Physics 2021-08-26 Akira Sone , Sebastian Deffner

The proper definition of entropy is fundamental to the relationship between statistical mechanics and thermodynamics. It also plays a major role in the recent debate about the validity of the concept of negative temperature. In this paper,…

Statistical Mechanics · Physics 2015-11-18 Robert H. Swendsen

The charging of a quantum battery by a four-stroke quantum machine that works either as an engine or a refrigerator is investigated. The presented analysis provides the energetic behavior of the combined system in terms of the heat and…

Quantum Physics · Physics 2022-11-11 Jeongrak Son , Peter Talkner , Juzar Thingna

Going beyond isolated system dynamics, we examine how local and spatially correlated reservoirs influence the work extraction in quantum batteries. By employing a one-dimensional spin-1/2 model coupled to baths via dephasing and…

Quantum Physics · Physics 2025-09-30 Sejal Ahuja , Tanoy Kanti Konar , Aditi Sen De

The challenge of storing energy efficiently and sustainably is highly prominent within modern scientific investigations. Due to the ongoing trend of miniaturization, the design of expressly quantum storage devices is itself a crucial task…

Quantum Physics · Physics 2024-04-01 C. A. Downing , M. S. Ukhtary

Machines are only Carnot efficient if they are reversible, but then their power output is vanishingly small. Here we ask, what is the maximum efficiency of an irreversible device with finite power output? We use a nonlinear scattering…

Mesoscale and Nanoscale Physics · Physics 2014-04-23 Robert S. Whitney

We discuss the possibility of reaching the Carnot efficiency by heat engines (HEs) out of quasi-static conditions at nonzero power output. We focus on several models widely used to describe the performance of actual HEs. These models…

Statistical Mechanics · Physics 2018-04-06 Viktor Holubec , Artem Ryabov

Accurately describing work extraction from a quantum system is a central objective for the extension of thermodynamics to individual quantum systems. The concepts of work and heat are surprisingly subtle when generalizations are made to…

Quantum Physics · Physics 2015-03-30 Felix C. Binder , Sai Vinjanampathy , Kavan Modi , John Goold

Quantum coherence has been demonstrated in various systems including organic solar cells and solid state devices. In this letter, we report the lower and upper bounds for the performance of quantum heat engines determined by the efficiency…

Quantum Physics · Physics 2018-04-18 Konstantin E. Dorfman , Dazhi Xu , Jianshu Cao

The role of quantum entanglement in thermodynamical systems remains elusive. Does entanglement result in thermodynamic advantages or does it impose fundamental limitations? Here, we unambiguously quantify the amount of heat and work in a…

Quantum Physics · Physics 2026-03-23 Joan Alba , Laura Ares , Jan Sperling , Julien Pinske

Giving a universal upper bound on the power output of heat engines is a long-standing open problem. We tackle this problem for generic quantum machines in self-contained formulation by carefully including the switching process of the…

Quantum Physics · Physics 2018-01-03 Kosuke Ito , Takayuki Miyadera

We derive the statistics of the efficiency under the assumption that thermodynamic fluxes fluctuate with normal law, parametrizing it in terms of time, macroscopic efficiency, and a coupling parameter $\zeta$. It has a peculiar behavior: No…

Statistical Mechanics · Physics 2015-02-19 Matteo Polettini , Gatien Verley , Massimiliano Esposito

We consider the task of extracting work from quantum systems in the resource theory perspective of thermodynamics, where free states are arbitrary thermal states, and allowed operations are energy conserving unitary transformations. Taking…

Quantum Physics · Physics 2013-02-13 Paul Skrzypczyk , Anthony J. Short , Sandu Popescu