title: Coherent dynamics of a flux qubit coupled to a harmonic oscillator.
abstract: In the emerging field of quantum computation and quantum information, superconducting devices are promising candidates for the implementation of solid-state quantum bits (qubits). Single-qubit operations, direct coupling between two qubits and the realization of a quantum gate have been reported. However, complex manipulation of entangled states-such as the coupling of a two-level system to a quantum harmonic oscillator, as demonstrated in ion/atom-trap experiments and cavity quantum electrodynamics-has yet to be achieved for superconducting devices. Here we demonstrate entanglement between a superconducting flux qubit (a two-level system) and a superconducting quantum interference device (SQUID). The latter provides the measurement system for detecting the quantum states; it is also an effective inductance that, in parallel with an external shunt capacitance, acts as a harmonic oscillator. We achieve generation and control of the entangled state by performing microwave spectroscopy and detecting the resultant Rabi oscillations of the coupled system.
authors.affiliation: Quantum Transport group, Kavli Institute of NanoScience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands. chiorescu@pa.msu.edu
authors.forename: I
authors.initials: I
authors.lastname: Chiorescu
authors.forename: P
authors.initials: P
authors.lastname: Bertet
authors.forename: K
authors.initials: K
authors.lastname: Semba
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: C J P M
authors.initials: CJ
authors.lastname: Harmans
authors.forename: J E
authors.initials: JE
authors.lastname: Mooij