Dynamic transition in Landau-Zener-St\"uckelberg interferometry of dissipative systems: the case of the flux qubit

TL;DR

This paper investigates how dissipative environments affect Landau-Zener-Stuckelberg interference in flux qubits, revealing a dynamic transition in interference patterns influenced by bath resonances and system parameters.

Contribution

It introduces a detailed numerical analysis of the dynamic transition in LZS interference patterns in multilevel flux qubits coupled to an Ohmic bath, highlighting the impact of resonant modes.

Findings

Identification of a symmetry change in LZS interference patterns

Resonant modes can impede the dynamic transition

Analysis based on Floquet-Markov approach for realistic models

Abstract

We study Landau-Zener-Stuckelberg (LZS) interferometry in multilevel systems coupled to an Ohmic quantum bath. We consider the case of superconducting flux qubits driven by a dc+ac magnetic fields, but our results can apply to other similar systems. We find a dynamic transition manifested by a symmetry change in the structure of the LZS interference pattern, plotted as a function of ac amplitude and dc detuning. The dynamic transition is from a LZS pattern with nearly symmetric multiphoton resonances to antisymmetric multiphoton resonances at long times (above the relaxation time). We also show that the presence of a resonant mode in the quantum bath can impede the dynamic transition when the resonant frequency is of the order of the qubit gap. Our results are obtained by a numerical calculation of the finite time and the asymptotic stationary population of the qubit states, using the Floquet-Markov approach to solve a realistic model of the flux qubit considering up to 10 energy levels.