Decoherence and relaxation of a qubit coupled to an Ohmic bath directly and via an intermediate harmonic oscillator

As we choosing suitable parameters the qubits in spin-boson (SB) and spin-intermediate harmonic oscillator-bath (SIB) models have almost same decoherence and relaxation. The decoherence and the relaxation of the qubit in SIB model can be modulated though changing the correlative parameters in the system.