Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 10: Superconductivity - Tunneling, Josephson Junctions, SQUIDs

TT 10.9: Talk

Saturday, March 5, 2005, 10:30–10:45, TU H104

1/f noise measurements on sub-micron Josephson junctions — •J. Eroms, J.H. Plantenberg, R.N. Schouten, A.H. Verbruggen, C.J.P.M. Harmans, and J.E. Mooij — Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, The Netherlands

Superconducting qubits belong to the most promising systems in solid state quantum information processing. They are explored by a number of groups in different configurations, and control of single and two-qubit systems is progressing rapidly. However, decoherence is still a serious issue. Low-frequency fluctuations in the critical current are believed to be an important source of decoherence, as was pointed out e.g. in Ref. 1. This article also gives a universal noise figure based on noise measurements published over the last two decades. Tocharacterize and improve our junction fabrication we have therefore measured 1/f noise in the tunnel resistance of sub-micron Josephson junctions at temperatures down to 300 mK. We used a bridge configuration of two identical junctions and measured the voltage noise with a cross-correlation technique. The noise in our devices was significantly lower than the value expected from the data in Ref. 1.

[1] D.J. Van Harlingen et al., Phys. Rev. B 70, 064517 (2004).