Liouville space description of thermofields and their generalisations

@inproceedings{Barnett1987LiouvilleSD,
  title={Liouville space description of thermofields and their generalisations},
  author={Stephen Mark Barnett and Brian James Dalton},
  year={1987}
}
The thermofield representation of a thermal state by a pure-state wavefunction in a doubled Hilbert space is generalised to arbitrary and pure states. The authors employ a Liouville space formalism to investigate the connection between these generalised thermofield wavefunctions and a generalised thermofield state vector in Liouville space which is valid for all cases of the quantum density operator. The system dynamics in the Schrodinger and Heisenberg pictures are discussed.