title: Quantum and classical chirps in an anharmonic oscillator.
abstract: We measure the state dynamics of a tunable anharmonic quantum system, the Josephson phase circuit, under the excitation of a frequency-chirped drive. At small anharmonicity, the state evolves like a wave packet-a characteristic response in classical oscillators; in this regime, we report exponentially enhanced lifetimes of highly excited states, held by the drive. At large anharmonicity, we observe sharp steps, corresponding to the excitation of discrete energy levels. The continuous transition between the two regimes is mapped by measuring the threshold of these two effects.
authors.affiliation: Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Yoni
authors.initials: Y
authors.lastname: Shalibo
authors.forename: Ya'ara
authors.initials: Y
authors.lastname: Rofe
authors.forename: Ido
authors.initials: I
authors.lastname: Barth
authors.forename: Lazar
authors.initials: L
authors.lastname: Friedland
authors.forename: Radoslaw
authors.initials: R
authors.lastname: Bialczack
authors.forename: John M
authors.initials: JM
authors.lastname: Martinis
authors.forename: Nadav
authors.initials: N
authors.lastname: Katz