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arXiv · 1805.07280

Confocal Annular Josephson Tunnel Junctions with Large Eccentricity

Roberto Monaco·Jesper Mygind·Lyudmila V. Filippenko
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Abstract

Confocal Annular Josephson Tunnel Junctions (CAJTJs) which are the natural generalization of the circular annular Josephson tunnel junctions, have a rich nonlinear phenomenology due to the intrinsic non-uniformity of their planar tunnel barrier delimited by two closely spaced confocal ellipses. In the presence of a uniform magnetic field in the barrier plane, the periodically changing width of the elliptical annulus generates a asymmetric double-well for a Josephson vortex trapped in a long and narrow CAJTJ. The preparation and readout of the vortex pinned in one of the two potential minima, which are important for the possible realization of a vortex qubit, have been numerically and experimentally investigated for CAJTJs with the moderate aspect ratio 2:1. In this work we focus on the impact of the annulus eccentricity on the properties of the vortex potential profile and study the depinning mechanism of a fluxon in more eccentric samples with aspect ratio 4:1. We also discuss the effects of the temperature-dependent losses as well as the influence of the current and magnetic noise.

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Roberto Monaco, Jesper Mygind, Lyudmila V. Filippenko. 2018-05-17. Confocal Annular Josephson Tunnel Junctions with Large Eccentricity. https://doi.org/10.1007/s10909-018-1977-1

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