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

TL;DR

This study uses numerical path integral methods to compare how qubits decohere and relax when coupled to low- and medium-frequency Ohmic baths directly or via a harmonic oscillator, revealing model-dependent differences.

Contribution

It provides a detailed comparison of decoherence and relaxation behaviors in spin-boson and spin-intermediate harmonic oscillator models with different bath frequencies.

Findings

Qubits in SB and SIB models behave similarly with low-frequency baths.

Differences emerge in medium-frequency baths between the two models.

Modulating coupling coefficients and oscillator frequency affects decoherence in SIB model.

Abstract

Using the numerical path integral method we investigate the decoherence and relaxation of qubits in spin-boson (SB) and spin-intermediate harmonic oscillator (IHO)-bath (SIB) models. The cases that the environment baths with low and medium frequencies are investigated. It is shown that the qubits in SB and SIB models have the same decoherence and relaxation as the baths with low frequencies. However, the qubits in the two models have different decoherence and relaxation as the baths with medium frequencies. The decoherence and relaxation of the qubit in SIB model can be modulated through changing the coupling coefficients of the qubit-IHO and IHO-bath and the oscillation frequency of the IHO.