Josephson radiation from gapless Andreev bound states in HgTe-based topological junctions

2016/03/31 by Russell S. Deacon, Jonas Wiedenmann, Erwann Bocquillon +9 · 1 citation
Physics and Astronomy · #cond-mat.mes-hall #cond-mat.supr-con

paper · pdf · doi:10.1103/physrevx.7.021011

published as Phys. Rev. X 7, 021011 (2017) · Updated version, with additional modeling

arxiv created 2016/08/18 · arxiv updated 2017/04/26

Abstract

Frequency analysis of the rf emission of oscillating Josephson supercurrent is a powerful passive way of probing properties of topological Josephson junctions. In particular, measurements of the Josephson emission enables to detect the expected presence of topological gapless Andreev bound states that give rise to emission at half the Josephson frequency f_J, rather than conventional emission at f_J. Here we report direct measurement of rf emission spectra on Josephson junctions made of HgTe-based gate-tunable topological weak links. The emission spectra exhibit a clear signal at half the Josephson frequency f_{\rm J}/2. The linewidths of emission lines indicate a coherence time of 0.3-\SI4ns for the f_{\rm J}/2 line, much shorter than for the f_{\rm J} line (3-\SI4ns). These observations strongly point towards the presence of topological gapless Andreev bound states, and pave the way for a future HgTe-based platform for topological quantum computation.

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