  Thermofield dynamics (TFD) approach is a real time quantum field method for
dealing with finite temperature quantum states in a purified version of usual
density operator formalism at finite temperature. In the domain of quantum
information, TFD represents a quite promising direction for dealing with qubits
under thermal influence and can also be associated to Gaussian states. Here, we
propose a generalized TFD mean expectation for the case of thermofield qubits
considering the action of gate operators. We propose quantum teleportation
protocols involving thermofield states, considering thermal-to-thermal and
thermal-to-non-thermal transfering cases. In particular, we discuss the case in
which Alice and Bob are at different temperatures. Action of gate operators on
the result of the Mandel parameter for thermofields and on Gibbs-like density
operators are also discussed. The no-cloning and non-broadcasting theorems in
TFD are also considered and cases of superposed thermofield states and maps
connecting thermofield vacua at different temperatures are also addressed and
associated to metastable and non-equilibrium scenarios.
