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arXiv · 1609.05241

Thermal fluctuations of the Josephson current in a ring of superconducting grains

D. A. Garanin·E. M. Chudnovsky
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Abstract

Thermal fluctuations of the Josephson current $I$ induced by the magnetic flux through a ring of $N$ superconducting grains are studied. When a half-fluxon is threading the ring, $I$ exhibits incoherent transitions between the two degenerate states due to thermal phase slips. We propose a new numerical method to deal with both equilibrium and dynamic properties of Josephson systems. Computed transition rate has the form $Γ= A(N)\exp[-B(N)/T]$, where $B(N)$ agrees with the analytical result derived for the energy barrier associated with phase slips. In the non-degenerate case (e.g., at a quarter-fluxon) the equilibrium value of $I$ decreases with $T$ due to harmonic excitations and then gets destroyed by phase slips.

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D. A. Garanin, E. M. Chudnovsky. 2016-09-29. Thermal fluctuations of the Josephson current in a ring of superconducting grains. https://doi.org/10.1103/physrevb.95.014520

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