Europhys. Lett.
Volume 67, Number 6, September 2004
Page(s) 1004 - 1010
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 September 2004
Europhys. Lett., 67 (6), pp. 1004-1010 (2004)
DOI: 10.1209/epl/i2004-10149-x

Coupling Josephson qubits via a current-biased information bus

L. F. Wei1, 2, Yu-xi Liu1 and Franco Nori1, 3

1  Frontier Research System, The Institute of Physical and Chemical Research (RIKEN) Wako-shi, Saitama, 351-0198, Japan
2  Institute of Quantum Optics and Quantum Information, Department of Physics Shanghai Jiaotong University - Shanghai 200030, PRC
3  Center for Theoretical Physics, Physics Department, CSCS The University of Michigan - Ann Arbor, MI 48109-1120, USA

(Received 1 March 2004; accepted in final form 19 July 2004)

Josephson qubits without direct interaction can be effectively coupled by sequentially connecting them to an information bus: a current-biased large Josephson junction treated as an oscillator with adjustable frequency. The coupling between any qubit and the bus can be controlled by modulating the magnetic flux applied to that qubit. This tunable and selective coupling provides two-qubit entangled states for implementing elementary quantum logic operations, and for experimentally testing Bell's inequality.

74.50.+r - Tunneling phenomena; point contacts, weak links, Josephson effects.
03.67.Lx - Quantum computation.
03.65.Ud - Entanglement and quantum nonlocality (e.g. EPR paradox, Bell's inequalities, GHZ states, etc.).

© EDP Sciences 2004