Revisiting the quantum Szilard engine with fully quantum considerations

By considering level shifting during the insertion process we revisit the quantum Szilard engine (QSZE) with fully quantum consideration. We derive the general expressions of the heat absorbed from thermal bath and the total work done to the environment by the system in a cycle with two different cyclic strategies. We find that only the quantum information contributes to the absorbed heat, and the classical information acts like a feedback controller and has no direct effect on the absorbed heat. This is the first demonstration of the different effects of quantum information and classical information for extracting heat from the bath in the QSZE. Moreover, when the well width L→∞L→∞ or the temperature of the bath T→∞T→∞ the QSZE reduces to the classical Szilard engine (CSZE), and the total work satisfies the relation Wtot=kBTln2 as obtained by Sang Wook Kim et al. [S.W. Kim, T. Sagawa, S. De Liberato, M. Ueda, Phys. Rev. Lett. 106 (2011) 070401] for one particle case.

► For the first time analyze the QSZE by considering energy level shifts. ► Find different roles played by classical and quantum information in the QSZE. ► The amount of work extracted depends on the cyclic strategies of the QSZE. ► Verify that the QSZE will reduce to the CSZE in the classical limits.