Entanglement of non-equilibrium finite-spin systems with external fields

Koichi Nakagawa

Published 2015-02-28Version 1

We study entanglement of non-equilibrium finite-spin systems with non-competitive external fields using thermofield dynamics (TFD) for both traditional and extended cases. The extended density matrix and the extended entanglement entropy of the systems are derived in this formulation, and it is found that the effects of the external fields can be obtained for the entangled state through this approach. Consequently, the applicability of the TFD-based method to describe quantum entanglement is confirmed in both non-dissipative and dissipative cases.