A. Murphy, P. Weinberg, T. Aref, U. Coskun, V. Vakaryuk, A. Levchenko, A. Bezryadin
We perform measurements of switching current on different types of superconducting weak links and systematically study higher moments of the switching current distributions. We employ two types of devices in which a weak link is formed either by a superconducting nanowire or by a graphene flake subject to proximity effect. We find that, independently on the nature of the weak link, the third moment (skewness) of the distribution is universally close to -1 both in thermal and quantum regimes, thus implying manifestly non-Gaussian statistics. The fourth moment (kurtosis) also takes a universal value close to 5. The discovered universality of skewness and kurtosis is confirmed by the analytical model. Our numerical analysis shows that introduction of extraneous noise into the system leads to significant deviations from the universal values. We suggest to use the universality of higher moments as a robust tool to check against undesirable effects on noise.
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http://arxiv.org/abs/1303.2620
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