Regensburg 2004 – scientific programme

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TT: Tiefe Temperaturen

TT 29: Quantenkoh
ärenz und Quanteninformationssysteme II

TT 29.6: Talk

Thursday, March 11, 2004, 15:45–16:00, H19

Decoherence of superconducting qubits due to phonons — •Christian Helm¹, L.B. Ioffe², V.B. Geshkenbein¹, and G. Blatter¹ — ¹ETH Hönggerberg, Institut fuer theoretische Physik, Zürich — ²Department of Physics and Astronomy, Rutgers University, Piscataway, USA

Decoherence is the main adversary of the unitary time evolution governing the quantum systems, which provide the hardware for a future quantum information technology based on solid state devices. Here, we discuss a fundamental limitation for the coherent operation of superconducting quantum bits based on Josephson junctions due to phonon radiation (Such an effect was observed e.g. in C. Helm at al. PRL 79 (1997),737). We find that recently reported quality factors may be explained in terms of decoherence from phonon radiation, which therefore might be the limiting factor in current experiments. We show the way to reduce the impact of this source of decoherence, e.g. by a choice of materials with appropriate elastic properties or by comparing various qubit designs.

16:00 Pause