Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 32: Transport: Quantum Coherence and Quantum Information Systems - Part 2

TT 32.2: Vortrag

Donnerstag, 30. März 2006, 14:15–14:30, HSZ 304

Inductive effects in tunable capacitive coupling of charge qubits — •Carsten Hutter and Alexander Shnirman — Institut für Theoretische Festkörperphysik, Universität Karlsruhe, D–76128 Karlsruhe, Germany

Recently, tunable capacitive [1] and inductive [2] coupling of Josephson charge and flux qubits have been proposed. Here, we concentrate on coupling of charge qubits via a Josephson junction, which provides a tunable effective capacitance. For this situation, it was suggested [3], that the capacitive coupling could be accompanied by an inductive one.
We clarify the situation by considering the limits where the Josephson energy of the coupling junction is much greater (much smaller) than its charging energy, E_J≫ E_c   (E_J≪ E_c). In the limit E_J≪ E_c, the inductive coupling appears as a small correction to the capacitive one. It will however play a role at the point, where the capacitive coupling vanishes. In the limit E_J≫ E_c, we find that the inductive coupling dominates over the capacitive one.
[1] D. V. Averin and C. Bruder, Phys. Rev. Lett. 91, 057003 (2003).
[2] B. L. T. Plourde et al., Phys. Rev. B 70, 140501(R) (2004).
[3] A. Zorin, cond-mat/0510435 (2005)