Dynamic behavior of Josephson-junction qubits: crossover between Rabi oscillations and Landau–Zener transitions

Abstract

We study the dynamic behavior of a quantum two-level system with periodically varying parameters by solving numerically the master equation for the density matrix. Two limiting cases are considered: multiphoton Rabi oscillations and Landau–Zener transitions. The approach is applied to the description of the dynamics of superconducting qubits. In particular, the case of the interferometer- type charge qubit with periodically varying parameters (gate voltage or magnetic flux) is investigated. The time-averaged energy level populations are calculated as functions of the qubit’s control parameters.