Landau-Zener transitions in qubits controlled by electromagnetic fields

TL;DR

This paper studies how electromagnetic fields affect Landau-Zener transitions in qubits, revealing the dependence on field parameters and phase, with analytical and numerical analysis applicable to microwave and magnetic systems.

Contribution

It introduces a model combining Landau-Zener and Rabi problems, analyzing the impact of field amplitude, frequency, and phase on transition probabilities in qubits.

Findings

Transition probabilities depend on Rabi interaction parameters.

Analytical results agree with numerical solutions in different frequency regimes.

Static phase influences time-reversal symmetry and transition outcomes.

Abstract

We investigate the influence of a dipole interaction with a classical radiation field on a qubit during a continuous change of a control parameter. In particular, we explore the non-adiabatic transitions that occur when the qubit is swept with linear speed through resonances with the time-dependent interaction. Two classical problems come together in this model: the Landau-Zener and the Rabi problem. The probability of Landau-Zener transitions now depends sensitively on the amplitude, the frequency and the phase of the Rabi interaction. The influence of the static phase turns out to be particularly strong, since this parameter controls the time-reversal symmetry of the Hamiltonian. In the limits of large and small frequencies, analytical results obtained within a rotating-wave approximation compare favourably with a numerically exact solution. Some physical realizations of the model are discussed, both in microwave optics and in magnetic systems.