Regensburg 2004 – scientific programme
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TT: Tiefe Temperaturen
TT 29: Quantenkoh
ärenz und Quanteninformationssysteme II
TT 29.7: Talk
Thursday, March 11, 2004, 16:15–16:30, H19
Controllable coupling of two charge qubits — •C. Bruder1 and D.V. Averin2 — 1Department of Physics and Astronomy, University of Basel, Klingelbergstrasse 82, CH-4056 Basel — 2Department of Physics and Astronomy, University of Stony Brook, SUNY, Stony Brook, NY 11794-3800
We propose and investigate a novel method for the controlled coupling of two Josephson charge qubits by means of a variable electrostatic transformer. The value of the coupling capacitance is given by the discretized curvature of the lowest energy band of a Josephson junction, which can be positive, negative, or zero. We calculate the charging diagram of the two-qubit system that reflects the transition from positive to negative through vanishing coupling. We also discuss how to implement a phase gate making use of the controllable coupling.
[1] D.V. Averin and C. Bruder, Phys. Rev. Lett. 91, 057003 (2003).