Dissipation and decoherence induced by collective dephasing in coupled-qubit system with a common bath

TL;DR

This paper investigates how collective dephasing from a common bath affects dissipation and decoherence in coupled-qubit systems, revealing interference effects that alter decay rates and coherence times.

Contribution

It demonstrates the impact of collective dephasing on dissipation and decoherence in coupled qubits, highlighting interference effects and providing decay rate calculations for various system sizes.

Findings

Interference between qubits alters dissipation rates.

Faster decoherence in non-single-excitation subspaces.

Slower dissipation in single-excitation subspaces.

Abstract

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 faster decoherence in the non-single-excitation subspaces and a slower dissipation (and decoherence) in the single-excitation subspace. For the system of multiple coupled qubits, we also find the slower dissipation in the single-excitation subspace and obtain the decay rates of the first excited states for different system sizes numerically. All our results on collective dephasing induced dissipation can be explained based on a simple model with Fermi's golden rule.