Fluctuation response of a minimal Kitaev chain in nonequilibrium states
Sergey Smirnov
DOI 10.1103/klwd-xckq · Physical Review B
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Abstract
Minimal Kitaev chains provide a unique platform to engineer Majorana states in quantum dots interacting via normal tunneling and crossed Andreev reflection specified by their amplitudes |ηn,a|. Here we analyze fluctuations of electric currents in a double quantum dot Kitaev chain using the differential effective charge q, that is the ratio of the differential shot noise and conductance. At low bias voltages V we find that q=e/2 in a very narrow vicinity of the point |ηn|=|ηa| whereas q=3e/2 almost in the whole sweet spot region and marks the range where the poor man's Majorana states largely govern the fluctuations. At high V we show that the sweet spot region is still characterized by q=3e/2 uniquely identifying the poor man's Majorana states using the high voltage tails. For |ηn|=0 or |ηa|=0 we obtain q=e at any V. Remarkably, before the asymptotic value q=e is reached for very high V, the maximal value q=2e is formed at |eV|=2|ηn|2+|ηa|2. The unique nature and potentially rich fluctuation behavior revealed in this work provide a stimulating ground for the next generation experiments on nonequilibrium shot noise in minimal Kitaev chains.