Rabi-like oscillations of an anharmonic oscillator: classical versus quantum interpretation

Julien Claudon (1) , Alex Zazunov (2) , Frank. W. J. Hekking (2) , Olivier Buisson (3)

1 INAC - Institut Nanosciences et Cryogénie
2 LPM2C - Laboratoire de physique et modélisation des milieux condensés
3 NEEL - QuantECA - Circuits électroniques quantiques Alpes

We have observed Rabi-like oscillations in a current-biased dc SQUID presenting enhanced coherence times compared to our previous realization~\cite{Claudon_PRL04}. This Josephson device behaves as an anharmonic oscillator which can be driven into a coherent superposition of quantum states by resonant microwave flux pulses. Increasing the microwave amplitude, we study the evolution of the Rabi frequency from the 2-level regime to the regime of multilevel dynamics. When up to $3$ levels are involved, the Rabi frequency is a clear signature of quantum behavior. At higher excitation amplitude, classical and quantum predictions for the Rabi frequency converge. This result is discussed in the light of a calculation of the Wigner function. In particular, our analysis shows that pronounced quantum interferences always appear in the course of the Rabi-like oscillations.

Mots clés: Rabi oscillation; superconducting quantum circuits; Quantum dynamics; superconducting qubits; quantum anharmonic oscillator

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

Julien Claudon, Alex Zazunov, Frank. W. J. Hekking, Olivier Buisson. Rabi-like oscillations of an anharmonic oscillator: classical versus quantum interpretation. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2008, 78, pp.184503. ⟨10.1103/PhysRevB.78.184503⟩. ⟨hal-00174630v2⟩