title: Comment on "Similarity between quantum mechanics and thermodynamics: Entropy, temperature, and Carnot cycle".
abstract: In the paper by Abe and Okuyama [Phys. Rev. E 83, 021121 (2011)], the quantum Carnot cycle of a simple two-state model of a particle confined in a one-dimensional infinite potential well is discussed. It is claimed that the state at the beginning of the quantum Carnot cycle is pure. After that, it is apparently transmuted to a mixed state if Clausius equality is imposed. We prove that this statement is incorrect. In particular, we prove that the state at the beginning of the cycle is mixed due to the process of measuring energy.
authors.affiliation: Laboratorio de Dinámica No Lineal y Sistemas Complejos, Centro de Física, Instituto Venezolano de Investigaciones Científicas, Caracas 1020-A, Venezuela.
authors.forename: L A
authors.initials: LA
authors.lastname: González-Díaz
authors.affiliation: Grupo de Información y Comunicación Cuántica DID-G79, Departamento de Física, Universidad Simón Bolívar, Sartenejas, Estado Miranda 89000, Venezuela.
authors.forename: S
authors.initials: S
authors.lastname: Díaz-Solórzano