Qubit interference at avoided crossings: The role of driving shape and bath coupling

TL;DR

This paper analyzes how the shape of periodic driving and bath coupling influence qubit interference patterns in dissipative quantum systems, providing analytical and numerical insights into their structure and decay.

Contribution

It introduces an analytical framework for understanding LZSM interference in dissipative qubits with general driving and bath coupling, highlighting the impact on interference patterns.

Findings

Interference patterns depend on the coupling operator to the bath.

Fourier transforms reveal arc structures reflecting driving shape.

Decay of interference features varies with dissipation and temperature.

Abstract

We derive the structure of the Landau-Zener-St\"uckelberg-Majorana (LZSM) interference pattern for a qubit that experiences quantum dissipation and is additionally subjected to time-periodic but otherwise general driving. A spin-boson Hamiltonian serves as model which we treat with a Bloch-Redfield master equation in Floquet basis. It predicts a peak structure that depends sensitively on the operator through which the qubit couples to the bath. The Fourier transforms of the LZSM patterns exhibit arc structures which reflect the shape of the driving. These features are captured by an effective time-independent Bloch equation which provides an analytical solution. Moreover, we determine the decay of these arcs as a function of dissipation strength and temperature.