Dear all,

I am modelling my two level system (spin) in the presence of a reservoir which causes dephasing of the TLS.  The system includes an arbitrary magnetic field and some other off-diagonal terms, such that the system Hamiltonian is not diagonal.

I have seen two ways of including dephasing, one which is presented in texts uses a collapse operator proportional to the Pauli Z operator acting on the spin.  Another [1] uses operators of the form |m> are the system eigenstates.

I can see that they both would induce elastic dephasing in the systems, so what is the difference between these approaches?  Is it simply to do with a global phase of the system?

Many thanks!

[1] D Tempel et al., Elsevier 391, 1, 130-142(2010)