scholarly journals Concepts of work in autonomous quantum heat engines

Quantum ◽  
2019 ◽  
Vol 3 ◽  
pp. 195 ◽  
Author(s):  
Wolfgang Niedenzu ◽  
Marcus Huber ◽  
Erez Boukobza
Keyword(s):  
Free Energy ◽  
Classical Limit ◽  
Entropy Change ◽  
Quantum Thermodynamics ◽  
Engine Efficiency ◽  
Heat Engines ◽  
Quantum Domain ◽  
Quantum Heat Engines ◽  
Non Equilibrium

One of the fundamental questions in quantum thermodynamics concerns the decomposition of energetic changes into heat and work. Contrary to classical engines, the entropy change of the piston cannot be neglected in the quantum domain. As a consequence, different concepts of work arise, depending on the desired task and the implied capabilities of the agent using the work generated by the engine. Each work quantifier---from ergotropy to non-equilibrium free energy---has well defined operational interpretations. We analyse these work quantifiers for a heat-pumped three-level maser and derive the respective engine efficiencies. In the classical limit of strong maser intensities the engine efficiency converges towards the Scovil--Schulz-DuBois maser efficiency, irrespective of the work quantifier.

scholarly journals Entropy Exchange and Thermodynamic Properties of the Single Ion Cooling Process

Entropy ◽  
2019 ◽  
Vol 21 (7) ◽  
pp. 650
Author(s):  
Jian-Guo Miao ◽  
Chun-Wang Wu ◽  
Wei Wu ◽  
Ping-Xing Chen
Keyword(s):  
Thermodynamic Properties ◽  
Heat Engine ◽  
Entropy Change ◽  
Quantum Thermodynamics ◽  
Cooling Process ◽  
Cooling Cycle ◽  
Heat Engines ◽  
Quantum Heat Engine ◽  
Ion Cooling ◽  
Complete Quantum

A complete quantum cooling cycle may be a useful platform for studying quantum thermodynamics just as the quantum heat engine does. Entropy change is an important feature which can help us to investigate the thermodynamic properties of the single ion cooling process. Here, we analyze the entropy change of the ion and laser field in the single ion cooling cycle by generalizing the idea in Reference (Phys. Rev. Lett. 2015, 114, 043002) to a single ion system. Thermodynamic properties of the single ion cooling process are discussed and it is shown that the Second and Third Laws of Thermodynamics are still strictly held in the quantum cooling process. Our results suggest that quantum cooling cycles are also candidates for the investigation on quantum thermodynamics besides quantum heat engines.

scholarly journals Quantum thermodynamics at low temperatures

2021 ◽  
Vol 52 (3) ◽  
pp. 15-17
Author(s):  
Jukka P. Pekola
Keyword(s):  
Quantum Information ◽  
Low Temperature ◽  
Low Temperatures ◽  
Quantum Information Processing ◽  
Quantum Systems ◽  
Quantum Thermodynamics ◽  
Heat Engines ◽  
Per Se ◽  
Working Media ◽  
Quantum Heat Engines

Low temperature phenomena and methods are quantum thermodynamics per se. Modern engineered quantum systems, for instance those used for superconducting quantum information processing and mesoscopic electron transport, provide working media for realizing devices such as quantum heat engines and refrigerators and a testbed for fundamental principles and phenomena in thermodynamics of quantum systems and processes.

Thermosize effects in a q-deformed fermion gas model

2018 ◽  
Vol 32 (20) ◽  
pp. 1850230 ◽  
Author(s):  
Mustafa Senay ◽  
Salih Kibaroglu
Keyword(s):  
Free Energy ◽  
Deformation Parameter ◽  
Helmholtz Free Energy ◽  
Quantum Gas ◽  
Grand Partition Function ◽  
Fermion Model ◽  
Heat Engines ◽  
Fermion Gas ◽  
Thermosize Effects ◽  
Quantum Heat Engines

We study the the high-temperature thermodynamic properties of the q-deformed fermion gas model by taking into account of the size effect of the gas particles. Starting from the logarithm of the grand partition function of the model, we calculate several thermodynamic functions of the model such as internal energy, entropy, and Helmholtz free energy by means of the deformation parameter q. Furthermore, the influences of the fermionic q-deformation on the thermosize effect in the confined deformed quantum gas systems such as the Seebeck-like and Peltier-like thermosize effects are discussed. Especially, we focus on the absorbed or released heat of the model in the Peltier-like thermosize effect. In the light of the results obtained in this work, we can conclude that the present q-deformed fermion model can be used to desing the new types of the micro-/nano-scaled quantum heat engines.

scholarly journals Thermodynamic Uncertainty Relation in Slowly Driven Quantum Heat Engines

2021 ◽  
Vol 126 (21) ◽  
Author(s):  
Harry J. D. Miller ◽  
M. Hamed Mohammady ◽  
Martí Perarnau-Llobet ◽  
Giacomo Guarnieri
Keyword(s):  
Uncertainty Relation ◽  
Heat Engines ◽  
Quantum Heat Engines

Probing the conformational energetics of alkyl thiols on gold surfaces by means of a morphing/steering non-equilibrium tool

2015 ◽  
Vol 17 (12) ◽  
pp. 8038-8052 ◽  
Author(s):  
Andrea Piserchia ◽  
Mirco Zerbetto ◽  
Diego Frezzato
Keyword(s):  
Free Energy ◽  
Gold Surface ◽  
Gold Surfaces ◽  
Jarzynski’S Equality ◽  
Torsion Free ◽  
Non Equilibrium

Jarzynski's equality is applied to compute the torsion free energy, bond-by-bond, for a probe alkyl thiol tethered to a gold surface.

scholarly journals The maximum efficiency of nano heat engines depends on more than temperature

Quantum ◽  
2019 ◽  
Vol 3 ◽  
pp. 177 ◽  
Author(s):  
Mischa P. Woods ◽  
Nelly Huei Ying Ng ◽  
Stephanie Wehner
Keyword(s):  
Second Law Of Thermodynamics ◽  
Maximum Efficiency ◽  
Second Law ◽  
Single Shot ◽  
Free Energies ◽  
Heat Engines ◽  
A Value ◽  
Quantum Protocols ◽  
Additional Constraints ◽  
Quantum Heat Engines

Sadi Carnot's theorem regarding the maximum efficiency of heat engines is considered to be of fundamental importance in thermodynamics. This theorem famously states that the maximum efficiency depends only on the temperature of the heat baths used by the engine, but not on the specific structure of baths. Here, we show that when the heat baths are finite in size, and when the engine operates in the quantum nanoregime, a revision to this statement is required. We show that one may still achieve the Carnot efficiency, when certain conditions on the bath structure are satisfied; however if that is not the case, then the maximum achievable efficiency can reduce to a value which is strictly less than Carnot. We derive the maximum efficiency for the case when one of the baths is composed of qubits. Furthermore, we show that the maximum efficiency is determined by either the standard second law of thermodynamics, analogously to the macroscopic case, or by the non increase of the max relative entropy, which is a quantity previously associated with the single shot regime in many quantum protocols. This relative entropic quantity emerges as a consequence of additional constraints, called generalized free energies, that govern thermodynamical transitions in the nanoregime. Our findings imply that in order to maximize efficiency, further considerations in choosing bath Hamiltonians should be made, when explicitly constructing quantum heat engines in the future. This understanding of thermodynamics has implications for nanoscale engineering aiming to construct small thermal machines.

scholarly journals Duality and hidden equilibrium in transport models

2020 ◽  
Vol 9 (4) ◽  
Author(s):  
Rouven Frassek ◽  
Cristian Giardina ◽  
Jorge Kurchan
Keyword(s):  
Free Energy ◽  
Time Reversal ◽  
Large Family ◽  
Equilibrium States ◽  
Transport Models ◽  
Good Opportunity ◽  
The Past ◽  
Non Equilibrium

A large family of diffusive models of transport that have been considered in the past years admit a transformation into the same model in contact with an equilibrium bath. This mapping holds at the full dynamical level, and is independent of dimension or topology. It provides a good opportunity to discuss questions of time reversal in out of equilibrium contexts. In particular, thanks to the mapping one may define the free energy in the non-equilibrium states very naturally as the (usual) free energy of the mapped system.

Theoretical Thermodynamic Analysis and Phase Analysis of AZ91D/Flyash Composites

2014 ◽  
Vol 788 ◽  
pp. 604-607
Author(s):  
Hong Chao Chu ◽  
Si Rong Yu ◽  
Cui Xiang Wang ◽  
Qi Lou
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Minimum Principle ◽  
Solution Treatment ◽  
Entropy Change ◽  
Treatment Temperature ◽  
Free Energy Change ◽  
Energy Change ◽  
Solution Treatment Temperature ◽  
Gibbs Free Energy Change

The thermodynamic calculation is valuable for judging the feasibility of a reaction. In the present paper, the enthalpy change (∆HR), entropy change (∆SR) and Gibbs free energy change (∆GR) among various components in AZ91D Mg alloy-Cenosphere composites (FAC/AZ91D) were calculated. Through the calculation, we obtained the relationships between the Gibbs free energy changes and temperatures. The difficulty degree of every potential reaction could be directly reflected by the correlation curve between the temperature and the Gibbs free energy change. The analysis result provided the theoretical basis for the reaction temperature and the solution treatment temperature of the FAC/AZ91D system. At the same time, the analysis based on the minimum principle of the reaction free energy revealed the final components (MgO, Mg2Si and MgAl2O4), which was partially similar to the result of XRD analysis (MgO, Mg2Si and Mg17Al12).

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