Finite frequency noise: an original probe for topological superconductors
Résumé
Topological superconductor nanowires constitute a strong candidate for the observation of Majorana bound states, which are expected to lie at each of its ends. Here, we suggest that current-current correlations probed at finite frequency offer a promising and original tool for the further characterization of the presence of such states in condensed matter systems, complementary to properties studied thus far. Focusing on a voltage-biased junction between a normal metal and a topological superconductor nanowire, we use the nonequilibrium Keldysh formalism to compute the finite frequency emission and absorption noise. Our results suggest that the presence of a Majorana bound state leads to a characteristic behavior of the noise spectrum at low frequency. While more work is still required to ensure that this constitutes an unambiguous signature, we could already check that different features arise for a nontopological system with a resonant level, exhibiting a zero-energy Andreev bound state.
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