Interband transitions and interference effects in superconducting qubits

Abstract

We investigate phase-sensitive interference effects in a periodically sin(2π f rf t)-driven, artificial two-state system connected to a microwave resonator at f LC ≃ 800 MHz. We observe two kinds of multiphoton transitions in the two-state system, accompanied by: (1) Several quanta from the drive at f rf and (2) one quantum at f rf and several at f LC . The former are described using phase-sensitive Landau–Zener transitions, while the latter are discussed in terms of vibronic transitions in diatomic molecules. Interference effects in the vibronic transitions governed by Franck–Condon coefficients are also considered.