Phys. Rev. A 80, 012322 (2009) [4 pages]Second law of thermodynamics and quantum feedback control: Maxwell’s demon with weak measurementsReceived 7 December 2008; published 17 July 2009 Recently Sagawa and Ueda [ Phys. Rev. Lett. 100 080403 (2008)] derived a bound on the work that can be extracted from a quantum system with the use of feedback control. For many quantum measurements their bound was not tight. We show that a tight version of this bound follows straightforwardly from recent work on Maxwell’s demon by Alicki et al. Open Syst. Inf. Dyn. 11 205 (2004)], for both discrete and continuous feedback control. Our analysis also shows that bare, efficient measurements always do non-negative work on a system in equilibrium, but do not add heat. © 2009 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevA.80.012322
DOI:
10.1103/PhysRevA.80.012322
PACS:
03.67.−a, 05.30.−d, 05.70.Ln, 03.65.Ta
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