Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 58: Poster Session Transport & Matter at Low Temperature
TT 58.34: Poster
Donnerstag, 14. März 2013, 15:00–19:00, Poster D
Current noise in disordered Josephson junctions — •Pierre-Luc Dallaire-Demers1, Mohammad Ansari2, and Frank Wilhelm-Mauch1 — 1Universität des Saarlandes, Saarbrücken, Deutschland — 2Institute for Quantum Computing, Waterloo, Canada
Josephson junctions are one of the fundamental building blocks of mesoscopic superconducting circuits. Despite being dissipationless, spurious low-energy Andreev bound states inside those junctions could provide an intrinsic microscopic mechanism for fluctuations of the current, therefore limiting the coherent operation time of superconducting quantum circuits. Models of bound states arising from pinholes in different models of disorder were investigated and their current noise signatures were characterized with respect to temperature, phase difference and sample-to-sample fluctuations of the conductance. In this theoretical work, it is shown that the low-frequency noise signature of Josephson junctions is a property specific to each individual sample independent of the fabrication process. Furthermore, the comparison of sample-specific noise spectra and characteristic current-voltage relations reveals under which conditions the presence of those disorder-induced bound states may elude detection in a 4-probe measurement but still reveal themselves as dephasing of coherent observables in circuits dominated by inductive energy.