Year: 2007
Type: article
Abstract: Given a mixed quantum state ρ of a qudit, we consider any observable M as a kind of "thermometer" in the following sense. Given a source which emits pure states with certain distributions, we select distributions such that the appropriate average value of the observable M is equal to the average Tr M ρ of M in the state ρ. Among those distributions we find the most typical, namely, having the highest differential entropy. We call this distribution the conditional Gibbs ensemble as it turns out to be a Gibbs distribution characterized by a temperature-like parameter β. The expressions establishing the liaisons between the density operator ρ and its temperature parameter β are provided. Within this approach, the uniform mixed state has the highest "temperature," which tends to zero as the state in question approaches a pure state.
Authors: GEORGE PARFIONOV, ROMÀN R. ZAPATRIN
Institution: St Petersburg University
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2044588447