Decoherence and relaxation of qubits coupled to low- and medium-frequency Ohmic baths directly and via a harmonic oscillator

摘要

Using the numerical path integral method we investigate the decoherence andrelaxation of qubits in spin-boson (SB) and spin-intermediate harmonicoscillator (IHO)-bath (SIB) models. The cases that the environment baths withlow and medium frequencies are investigated. It is shown that the qubits in SBand SIB models have the same decoherence and relaxation as the baths with lowfrequencies. However, the qubits in the two models have different decoherenceand relaxation as the baths with medium frequencies. The decoherence andrelaxation of the qubit in SIB model can be modulated through changing thecoupling coefficients of the qubit-IHO and IHO-bath and the oscillationfrequency of the IHO.