We clarify the mathematical difficulty when for bosonic systems (i.e., unbounded operators) we rigorously construct a Liouville space, in which a Liouville operator acts, associated with a Hamiltonian. Including unbounded and non-quasi-free cases. We give thermo field dynamics as an expression equivalent to the Liouville space and operator. We investigate the mathematical properties of them, and thus we clarify the mathematical properties of the thermal state.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)