Higher Harmonic Supercurrents in Multi-Terminal Josephson Junctions

The dynamical properties of multi-terminal Josephson junctions have attracted interest, driven by the promise of new insights into synthetic topological phases of matter and Floquet states. This study has recently culminated in the discovery of Cooper multiplets, where the splitting of Cooper pairs allows a series of Andreev reflections which entangles four (or more) electrons. In this talk, we show that multiplet resonances can also emerge as a simple consequence of the three terminal RCSJ model. The supercurrent appears due to the absence of average phase dynamics at values that correspond to the multiplet condition nV1 = -mV2. Along these lines, the supercurrent carries large harmonic contributions in its current phase relation. Remarkably, these lines emerge in a nanofabricated three-terminal graphene Josephson junction, in an analog three terminal Josephson junction circuit, and in a simulated RCSJ model. We describe parameter considerations that best optimize the detection of these multiplet lines for future engineering of higher harmonic supercurrent flows.