Congratulations to Zhibo Niu for publishing  Experimental investigation of coherent ergotropy in a single spin system on Physical Review Letters as “Featured in Physics”!

Extracting work from an out-of-equilibrium system has been a central topic of classical thermodynamics and, in more recent years, of quantum thermodynamics. The concept of ergotropy, defined as the maximal amount of extractable work via cyclic unitary evolution, was brought up to quantify the work capacity of a quantum state. Lately, it has been pointed out that existence of quantum coherence would yield larger ergotropy theoretically. However, an experimental investigation remains absent to demonstrate the contribution of coherence in ergotropy because the measurement of ergotropy often requires complicated quantum state tomography. We have developed a method to measure ergotropy using an ancilla qubit and conducted a proof-of-principle experiment in a single spin system. Both the coherent and incoherent components of the ergotropy of a non-equilibrium state were successfully extracted. The increase in ergotropy induced by the increase in the coherence of the system was observed by varying the coherence of the state. Our work reveals the interplay between quantum thermodynamics and quantum information theory; future investigations could further explore the role other quantum attributes play in thermodynamic protocols. Moreover, our work can potentially guide the enhancement of both the capacity and efficiency of quantum devices operationally.

The contribution of this work has been reviewed by Professor Eric Lutz of University of Stuttgart in an article titled 'Quantum Coherence Boosts Quantum Work' at physics.aps.org.

 

https://doi.org/10.1103/PhysRevLett.133.180401

https://physics.aps.org/articles/v17/154