Berlin 2005 – scientific programme
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TT: Tiefe Temperaturen
TT 13: Transport - Quantum Coherence and Quantum Information Systems
TT 13.1: Talk
Saturday, March 5, 2005, 08:45–09:00, TU H3027
Relation between high- and low-frequency noise — •Alexander Shnirman1, Gerd Schön1, Ivar Martin2, and Yuriy Makhlin3 — 1Institut für Theoretische Festkörperphysik, Universität Karlsruhe — 2Los Alamos National Laboratory, Los Alamos, NM, USA — 3Landau Institute for Theoretical Physics, Moscow, Russia
Low-frequency (1/f) noise dominates the decoherence in most
superconducting qubits. Thus it is very important to
understand its origin and properties. Recently, coherent two-level systems
have been observed in Josephson junctions [1]. These systems influence
strongly qubits’ dynamics at high (≈ 10 GHz) frequencies.
In addition, recent experiments [2] indicate a
connection between the high- and low-frequency noise.
In this work we note that an ensemble of coherent two-level
systems produces simultaneously high- and low-frequency noise.
The relation between these two contributions depends on the
statistical properties of the ensemble. We analyze several
possible distribution functions and relate the results to the
known experimental facts. We also note that a similar relation
holds for ensembles of many-level fluctuators with discrete
spectrum.
R.W. Simmonds et al., Phys. Rev. Lett. 93, 035301 (2004)
O. Astafiev et al., cond-mat/0411216 (2004)