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arXiv · 1802.07205

Information gain and loss for a quantum Maxwell's demon

M. Naghiloo·J. J. Alonso·A. Romito·E. Lutz·K. W. Murch
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Abstract

We use continuous weak measurements of a driven superconducting qubit to experimentally study the information dynamics of a quantum Maxwell's demon. We show how information gained by a demon who can track single quantum trajectories of the qubit can be converted into work using quantum coherent feedback. We verify the validity of a quantum fluctuation theorem with feedback by utilizing information obtained along single trajectories. We demonstrate, in particular, that quantum backaction can lead to a loss of information in imperfect measurements. We furthermore probe the transition between information gain and loss by varying the initial purity of the qubit.

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M. Naghiloo, J. J. Alonso, A. Romito, E. Lutz, K. W. Murch. 2018-02-20. Information gain and loss for a quantum Maxwell's demon. https://doi.org/10.1103/physrevlett.121.030604

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