Dissipation and decoherence induced by collective dephasing in a coupled-qubit system with a common bath
Zhihai Wang, Yanjun Ji, Yong Li, Dong Zhou · Physical Review A · 2015
The longitudinal coupling of a system to the bath usually induces the pure dephasing of the system. In this paper, we study the collective dephasing induced dissipation and decoherence in a coupled-qubit system with a common bath. It is shown that compared with the case of the same system with independent baths, the interference between the dephasing processes of different qubits induced by the common bath significantly changes the dissipation of the system. For the system of two coupled qubits, the interference leads to a slower dissipation (and decoherence) in the single-excitation subspace. As the system size increases, we find that the decay rate of the first excited state in the single-excitation subspace will tend to be a constant in the case of a common bath and will drop to zero in the case of independent baths. All of our results on collective dephasing induced dissipation can be explained based on a simple model with Fermi's golden rule.