Dresden 2011 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 46: SC: Tunneling, Josephson Junctions, SQUIDs 1
TT 46.2: Vortrag
Donnerstag, 17. März 2011, 10:45–11:00, HSZ 301
Dependence of the macroscopic quantum tunneling rate on Josephson junction area — •Roland Schäfer1,2, Christoph Kaiser3, and Michael Siegel2,3 — 1Institut für Festkörperphysik, Karlsruhe Instituteof Technology, 76021 Karlsruhe — 2Center for Functional Nanostructures, 76128 Karlsruhe — 3Institut für Mikro- und Nanoelektronische Systeme, Karlsruhe Institute of Technology, 76187 Karlsruhe
We have carried out systematic Macroscopic Quantum Tunneling (MQT)
experiments on Nb/Al-AlOx/Nb Josephson junctions (JJs) of different
areas. Employing on-chip lumped element inductors, we have decoupled the
JJs from their environmental line impedances at the frequencies relevant
for MQT. This allowed us to study the crossover from the thermal to the
quantum regime in the low damping limit. A clear reduction of the crossover
temperature with increasing JJ size is observed and found to be in accord
with theory. Deviations of the observed quantum rate from theoretical
predictions are thoroughly analized and discussed in the framework of
Kramer’s [1] turnover problem.
H. A. Kramers, Physica (Utrecht), 7, 284 (1940).