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arXiv · 2108.00989

Phase-dependent microwave response of a graphene Josephson junction

Roy Haller·Gergő Fülöp·David Indolese·Joost Ridderbos·Rainer Kraft·Luk Yi Cheung·Jann Hinnerk Ungerer·Kenji Watanabe·Takashi Taniguchi·Detlef Beckmann·Romain Danneau·Pauli Virtanen·Christian Schönenberger
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Abstract

Gate-tunable Josephson junctions embedded in a microwave environment provide a promising platform to in-situ engineer and optimize novel superconducting quantum circuits. The key quantity for the circuit design is the phase-dependent complex admittance of the junction, which can be probed by sensing an rf SQUID with a tank circuit. Here, we investigate a graphene-based Josephson junction as a prototype gate-tunable element enclosed in a SQUID loop that is inductively coupled to a superconducting resonator operating at 3 GHz. With a concise circuit model that describes the dispersive and dissipative response of the coupled system, we extract the phase-dependent junction admittance corrected for self-screening of the SQUID loop. We decompose the admittance into the current-phase relation and the phase-dependent loss and as these quantities are dictated by the spectrum and population dynamics of the supercurrent-carrying Andreev bound states, we gain insight to the underlying microscopic transport mechanisms in the junction. We theoretically reproduce the experimental results by considering a short, diffusive junction model that takes into account the interaction between the Andreev spectrum and the electromagnetic environment, from which we deduce a lifetime of ~17 ps for non-equilibrium populations.

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Roy Haller, Gergő Fülöp, David Indolese, Joost Ridderbos, Rainer Kraft, Luk Yi Cheung, Jann Hinnerk Ungerer, Kenji Watanabe, Takashi Taniguchi, Detlef Beckmann, Romain Danneau, Pauli Virtanen, Christian Schönenberger. 2021-08-02. Phase-dependent microwave response of a graphene Josephson junction. https://doi.org/10.1103/physrevresearch.4.013198

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