Correlated charge transport in bilinear Josephson junction arrays: Why electrons don't like to be left behind

by Kelly Walker (MIT)

Monday 9 Feb 2015, 11:00 → 12:00 Europe/Stockholm

Nordita West (122:026)

Quantum metrology aims to define all SI units of measurement in terms of physical constants. The SI unit of current – the ampere – is the last remaining fundamental unit of electricity still defined by “classical” measurement. This research aims to develop a new definition of the ampere in terms of quantum mechanical principles, using Josephson junction arrays – superconducting quantum circuits. Josephson junction arrays are potential candidates for current standards due to their nonlinearity, negligible energy dissipation, long coherence times, and large scalability. However, to achieve the precision necessary for current standards, the charge periodicity must be precisely controlled. This requires a detailed theoretical understanding of the microscopic processes within these devices. Furthermore, the current theoretical model of Josephson junction physics fails to predict several phenomena recently observed in experiment. This research begins with a detailed investigation of the transport properties of the circuits to develop a consistent and general microscopic theoretical model that correctly predicts and interprets these results. Consequently, results from our kinetic Monte-Carlo study of correlated transport in bilinear arrays of tunnel junctions consisting of two N = 50 junction arrays are presented. The interplay between competing charge carriers is also discussed.