Observing a quantum Maxwell demon at work
Proceedings of the National Academy of Sciences
National Academy of Sciences
In apparent contradiction to the laws of thermodynamics, Maxwell’s demon is able to cyclically extract work from a system in contact with a thermal bath exploiting the information about its microstate. The resolution of this paradox required the insight that an intimate relationship exists between information and thermodynamics. Here, we realize a Maxwell demon experiment that tracks the state of each constituent both in the classical and quantum regimes. The demon is a microwave cavity that encodes quantum information about a superconducting qubit and converts information into work by powering up a propagating microwave pulse by stimulated emission. Thanks to the high level of control of superconducting circuits, we directly measure the extracted work and quantify the entropy remaining in the demon’s memory. This experiment provides an enlightening illustration of the interplay of thermodynamics with quantum information.
This work was supported by the ANR under the grants 12-JCJC-TIQS and 13-JCJC-INCAL, by Ville de Paris through the grant Qumotel of the Emergence program and by the COST network MP1209 "Thermodynamics in the quantum regime". J.A. acknowledges support from EPSRC, grant EP/M009165/1, and the Royal Society
This is the author accepted manuscript. The final version is available from National Academy of Sciences via the DOI in this record.
Published online 3 July 2017