scholarly journals Quantum Heat Engines with Singular Interactions

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 978
Author(s):  
Nathan M. Myers ◽  
Jacob McCready ◽  
Sebastian Deffner
Keyword(s):  
Wave Function ◽  
Engine Performance ◽  
Interparticle Interactions ◽  
Quantum Devices ◽  
Singular Interaction ◽  
Heat Engines ◽  
Working Medium ◽  
Quantum Phenomena ◽  
Singular Interactions ◽  
Quantum Heat Engines

By harnessing quantum phenomena, quantum devices have the potential to outperform their classical counterparts. Here, we examine using wave function symmetry as a resource to enhance the performance of a quantum Otto engine. Previous work has shown that a bosonic working medium can yield better performance than a fermionic medium. We expand upon this work by incorporating a singular interaction that allows the effective symmetry to be tuned between the bosonic and fermionic limits. In this framework, the particles can be treated as anyons subject to Haldane’s generalized exclusion statistics. Solving the dynamics analytically using the framework of “statistical anyons”, we explore the interplay between interparticle interactions and wave function symmetry on engine performance.

scholarly journals Quantum Heat Engines with Complex Working Media, Complete Otto Cycles and Heuristics

Entropy ◽  
2021 ◽  
Vol 23 (9) ◽  
pp. 1149
Author(s):  
Ramandeep S. Johal ◽  
Venu Mehta
Keyword(s):  
Upper Bound ◽  
Necessary Conditions ◽  
Engine Performance ◽  
Extreme Case ◽  
Arbitrary Spin ◽  
Spin Model ◽  
Heat Engines ◽  
Working Medium ◽  
Working Media ◽  
Quantum Heat Engines

Quantum thermal machines make use of non-classical thermodynamic resources, one of which include interactions between elements of the quantum working medium. In this paper, we examine the performance of a quasi-static quantum Otto engine based on two spins of arbitrary magnitudes subject to an external magnetic field and coupled via an isotropic Heisenberg exchange interaction. It has been shown earlier that the said interaction provides an enhancement of cycle efficiency, with an upper bound that is tighter than the Carnot efficiency. However, the necessary conditions governing engine performance and the relevant upper bound for efficiency are unknown for the general case of arbitrary spin magnitudes. By analyzing extreme case scenarios, we formulate heuristics to infer the necessary conditions for an engine with uncoupled as well as coupled spin model. These conditions lead us to a connection between performance of quantum heat engines and the notion of majorization. Furthermore, the study of complete Otto cycles inherent in the average cycle also yields interesting insights into the average performance.

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

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.

Performance projections for functional CO2laser coupled quantum heat engines

2004 ◽  
Vol 51 (16-18) ◽  
pp. 2713-2725 ◽  
Author(s):  
Alan E. Hill ◽  
Yuri V. Rostovtsev ◽  
Marlan O. Scully
Keyword(s):  
Heat Engines ◽  
Quantum Heat Engines

scholarly journals Time–energy uncertainty principle for irreversible heat engines

2020 ◽  
Vol 378 (2170) ◽  
pp. 20190171 ◽  
Author(s):  
Rudolf Hanel ◽  
Petr Jizba
Keyword(s):  
Uncertainty Principle ◽  
Nonequilibrium Thermodynamics ◽  
Real Life ◽  
Ideal Gas ◽  
Irreversible Processes ◽  
Bohr Radius ◽  
Heat Engines ◽  
Working Medium ◽  
Semi Empirical ◽  
The Ideal

Even though irreversibility is one of the major hallmarks of any real-life process, an actual understanding of irreversible processes remains still mostly semi-empirical. In this paper, we formulate a thermodynamic uncertainty principle for irreversible heat engines operating with an ideal gas as a working medium. In particular, we show that the time needed to run through such an irreversible cycle multiplied by the irreversible work lost in the cycle is bounded from below by an irreducible and process-dependent constant that has the dimension of an action. The constant in question depends on a typical scale of the process and becomes comparable to Planck’s constant at the length scale of the order Bohr radius, i.e. the scale that corresponds to the smallest distance on which the ideal gas paradigm realistically applies. This article is part of the theme issue ‘Fundamental aspects of nonequilibrium thermodynamics’.

scholarly journals Cooperative efficiency boost for quantum heat engines

2019 ◽  
Vol 99 (2) ◽  
Author(s):  
David Gelbwaser-Klimovsky ◽  
Wassilij Kopylov ◽  
Gernot Schaller
Keyword(s):  
Heat Engines ◽  
Quantum Heat Engines

scholarly journals How Does Quantum Uncertainty Emerge from Deterministic Bohmian Mechanics?

2016 ◽  
Vol 15 (03) ◽  
pp. 1640010 ◽  
Author(s):  
A. Solé ◽  
X. Oriols ◽  
D. Marian ◽  
N. Zanghì
Keyword(s):  
Wave Function ◽  
Classical Mechanics ◽  
Bohmian Mechanics ◽  
The State ◽  
Quantum Uncertainty ◽  
Point Particles ◽  
Quantum Randomness ◽  
Quantum Dynamical ◽  
System Of Particles ◽  
Quantum Phenomena

Bohmian mechanics is a theory that provides a consistent explanation of quantum phenomena in terms of point particles whose motion is guided by the wave function. In this theory, the state of a system of particles is defined by the actual positions of the particles and the wave function of the system; and the state of the system evolves deterministically. Thus, the Bohmian state can be compared with the state in classical mechanics, which is given by the positions and momenta of all the particles, and which also evolves deterministically. However, while in classical mechanics it is usually taken for granted and considered unproblematic that the state is, at least in principle, measurable, this is not the case in Bohmian mechanics. Due to the linearity of the quantum dynamical laws, one essential component of the Bohmian state, the wave function, is not directly measurable. Moreover, it turns out that the measurement of the other component of the state — the positions of the particles — must be mediated by the wave function; a fact that in turn implies that the positions of the particles, though measurable, are constrained by absolute uncertainty. This is the key to understanding how Bohmian mechanics, despite being deterministic, can account for all quantum predictions, including quantum randomness and uncertainty.

Sign in / Sign up

Export Citation Format

Share Document