Drive-dependent dissipation in open quantum systems regularized by thermal fluctuations

We report an alternate formulation of the quantum master equation (QME) to describe the dynamics of a quantum system weakly coupled to a heat bath, in the presence of weak external drive. A key feature of this approach is the introduction of an explicit Hamiltonian to model the thermal fluctuations in the heat bath. We show that the resulting time coarse-grained dynamical equation for the quantum system has dissipators with a natural regulator, which emerges from an ensemble average over the fluctuations. Importantly, such regularized dissipators arise from the second-order contributions of both the external drive as well as the system-environment coupling. We show that the second-order drive terms, regularized to time-scales set by the fluctuations, result in dynamic drive-induced frequency shifts (such as Bloch-Siegert shifts) as well as drive-dependent relaxation phenomena (the Kramers-Kronig pair of the shift terms). We also present the experimental verification of the drive-induced dissipation terms using Nuclear Magnetic Resonance techniques. It is contemplated that such drive-induced dissipation will play important roles in quantum information processing.

1. A. Chakrabarti & R. Bhattacharyya, PRA, 97, 063837 (2018)
2. A. Chakrabarti & R. Bhattacharyya, EPL, 121, 57002 (2018)