MIDIT OFD CATS Modelling, Nonlinear Dynamics Optics and Fluid Dynamics Chaos and Turbulence Studies and Irreversible Thermodynamics Risø National Laboratory Niels Bohr Institute and Technical University of Denmark Building 128 Department of Chemistry Building 321 P.O. Box 49 University of Copenhagen DK-2800 Lyngby DK-4000 Roskilde DK-2100 Copenhagen Ø Denmark Denmark Denmark
by Klavs Hansen
Department of Physics
University of Jyvæskylæ
Thursday December 7, 2000, 14.00 h
at FYS, Bldg. 309, Room 250, DTU,
Abstract: Computing has to date been a technology based exclusively on information stored and processed as classical bits. Recently it it was realised that quantum information and processesing are very different from their classical counterparts and that a quantum computer can perform tasks that are virtually impossible for a classical computer. This understanding has triggered a large activity to present the first physical realisation of the qubit, the quantum bit, and to design and operate the logical elements to read out and manipulate it. Two particularly interesting candidates are the solid state system of a small superconducting island coupled weakly to the surroundings through Josephson junctions, the so-called Single Cooper Pair Box, and the flux qubit which is based on persistent currents in a superconducting loop. In the talk I will discuss the basic principle of the quantum computer, review ongoing attempts to construct qubits and present results from the work in Jyvæskylæ on the Cooper Pair Box and the decoherence time which is the time available for computing with these devices.