The extraction of work from quantum coherence

Abstract

The interplay between quantum-mechanical properties, such as coherence, and classical notions, such as energy, is a subtle topic at the forefront of quantum thermodynamics. The traditional Carnot argument limits the conversion of heat to work; here we critically assess the problem of converting coherence to work. Through a careful account of all resources involved in the thermodynamic transformations within a fully quantum-mechanical treatment, we show that there exist thermal machines extracting work from coherence arbitrarily well. Such machines only need to act on individual copies of a state and can be reused. On the other hand, we show that for any thermal machine with finite resources not all the coherence of a state can be extracted as work. However, even bounded thermal machines can be reused infinitely many times in the process of work extraction from coherence.

Comparison of incoherent operations and measures of coherence

“…Recently, researchers have used this distinction between coherent and incoherent states to construct resource theories of quantum coherence [1][2][3][4][5][6][7][8][9][10]. A general quantum resource theory consists of a class of "free" states along with a class of "free" or allowable operations [11].…”

Daemonic ergotropy: enhanced work extraction from quantum correlations

“…In particular, the role that quantum correlations and coherences in schemes for the extraction of work from quantum systems appears to be quite controversial. [15][16][17][18][19][20] Yet, the clarification of the relevance of genuinely quantum features would be key for the grounding of quantum thermodynamics as a viable route towards the construction of a framework for quantum technologies. [1][2][3][4] Indeed, the very tight link between thermodynamics and quantum entanglement 21 cries loud for the clarification of the role of quantum correlations as a resource for coherent thermodynamic processes and transformations.…”

Toward Physical Realizations of Thermodynamic Resource Theories

“…Modeling QFTs with TRTs could unlock testbeds and applications for TRTs. Further motivation appears in [61]: The authors study the "unlocking," aided by an external field, of work stored in coherence. The field suffers a back reaction.…”