title: Coherent frequency conversion in a superconducting artificial atom with two internal degrees of freedom.
abstract: By adding a large inductance in a dc-SQUID phase qubit loop, one decouples the junctions' dynamics and creates a superconducting artificial atom with two internal degrees of freedom. In addition to the usual symmetric plasma mode (s mode) which gives rise to the phase qubit, an antisymmetric mode (a mode) appears. These two modes can be described by two anharmonic oscillators with eigenstates |ns> and |na> for the s and a mode, respectively. We show that a strong nonlinear coupling between the modes leads to a large energy splitting between states |0s,1a> and |2s,0a>. Finally, coherent frequency conversion is observed via free oscillations between the states |0s,1a> and |2s,0a>.
authors.affiliation: Institut Néel, CNRS-Université Joseph Fourier, BP 166, 38042 Grenoble-cedex 9, France.
authors.forename: F
authors.initials: F
authors.lastname: Lecocq
authors.forename: I M
authors.initials: IM
authors.lastname: Pop
authors.forename: I
authors.initials: I
authors.lastname: Matei
authors.forename: E
authors.initials: E
authors.lastname: Dumur
authors.forename: A K
authors.initials: AK
authors.lastname: Feofanov
authors.forename: C
authors.initials: C
authors.lastname: Naud
authors.forename: W
authors.initials: W
authors.lastname: Guichard
authors.forename: O
authors.initials: O
authors.lastname: Buisson