Optimal efficiency of a noisy quantum heat engine

Abstract

In this article we use optimal control to maximize the efficiency of a quantum heat engine executing the Otto cycle in the presence of external noise. We optimize the engine performance for both amplitude and phase noise. In the case of phase damping we additionally show that the ideal performance of a noiseless engine can be retrieved in the adiabatic (long time) limit. The results obtained here are useful in the quest for absolute zero, the design of quantum refrigerators that can cool a physical system to the lowest possible temperature. They can also be applied to the optimal control of a collection of classical harmonic oscillators sharing the same time-dependent frequency and subjected to similar noise mechanisms. Finally, our methodology can be used for the optimization of other interesting thermodynamic processes.

Controlling open quantum systems: tools, achievements, and limitations

“…It will be concluded by briefly mentioning examples from other fields of current interest: Quantum optimal control for open systems has been employed in the context of quantum thermodynamics, in order to determine the optimal efficiency of a noisy heat engine [195]; biological chromophore complexes, in order to maximize exciton transfer [196,197]; molecules immersed in dissipative media, in order to maximally align them with respect to a laboratory axis [198][199][200]; molecular junctions, in order to control the current, shot noise and Fano factors [201]; as well as chemical reaction dynamics [202][203][204], including charge transfer in molecules [205], and surface photochemistry [206][207][208]. The numerous applications attest to the maturity as well as versatility of the quantum control toolbox [1].…”

Quantum supremacy of many-particle thermal machines

“…Current efforts towards the realization of a tunable QHE in the laboratory use a single-particle working medium, e.g., a confined ion in a modified Paul trap [8][9][10]. The optimization of this type of single-particle QHE has received considerable attention [8,9,[11][12][13][14][15][16][17]. By contrast, the performance of a QHE with a many-particle working medium remains essentially unexplored [18][19][20][21].…”

Fast atom transport and launching in a nonrigid trap

“…(15), while the evolution of the trap position is found substituting Eqs. (15) and (19) into Eq. (16).…”

“…There are different fields or applications where simultaneous transport and expansion or compression between initial and final states at rest is of relevance. In quantum heat engines and refrigerators [13][14][15][16][17][18][19][20][21][22] for example, the (thermodynamically) adiabatic expansion or compression strokes of the cycle could be realized simultaneously transporting the quantum working medium between baths at different locations. Also, when expanding or separating ion chains, which are basic processes to develop a scalable quantum-information architecture 23 , the effective dynamics of the normal modes involves simultaneous transport and frequency change 24,25 .…”