A Physical Explanation for Tilde System in Thermo Field Dynamics
arXiv:quant-ph/0102127 · doi:10.1142/S0217732301003607
Abstract
For a two-body quantum system, any pure state can be represented by a biorthogonal expression by means of Schmidt decomposition. Using this in the composite system which include a thermodynamic system and its surroundings, it is found that the tilde system in thermo field dynamics is just the surroundings of the real system.
10 pages. To be published in Modern Physics Letter A