An open question of fundamental importance in thermodynamics is howto describe the fluctuations of work for quantum coherent processes. In the standard approach, based on a projective energy measurement both at the beginning and at the end of the process, the first measurement destroys any initial coherence in the energy basis. Here we seek extensions of this approach which can possibly account for initially coherent states. We consider all measurement schemes to estimate work and require that (i) the difference of average energy corresponds to average work for closed quantum systems and that (ii) the work statistics agree with the standard two-measurement scheme for states with no coherence in the energy basis. We first show that such a scheme cannot exist. Next, we consider the possibility of performing collective measurements on several copies of the state and prove that it is still impossible to simultaneously satisfy requirements (i) and (ii). Nevertheless, improvements do appear, and in particular, we develop a measurement scheme that acts simultaneously on two copies of the state and allows us to describe a whole class of coherent transformations.

VL - 118 ER - TY - JOUR T1 - Extractable Work from Correlations JF - Physical Review X Y1 - 2015 A1 - Perarnau-Llobet, Marti A1 - Hovhannisyan, Karen V. A1 - Huber, Marcus A1 - Skrzypczyk, Paul A1 - Brunner, Nicolas A1 - Acín, Antonio VL - 5 UR - https://link.aps.org/doi/10.1103/PhysRevX.5.041011http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevX.5.041011/fulltexthttp://link.aps.org/article/10.1103/PhysRevX.5.041011 JO - Phys. Rev. X ER - TY - JOUR T1 - Thermodynamics of creating correlations: Limitations and optimal protocols JF - Physical Review E Y1 - 2015 A1 - Bruschi, David Edward A1 - Perarnau-Llobet, Marti A1 - Friis, Nicolai A1 - Hovhannisyan, Karen V. A1 - Huber, Marcus VL - 91 UR - https://link.aps.org/doi/10.1103/PhysRevE.91.032118http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevE.91.032118/fulltexthttp://link.aps.org/article/10.1103/PhysRevE.91.032118 JO - Phys. Rev. E ER -