A ballistic graphene superconducting microwave circuit
F.E. Schmidt (TU Delft - QN/Steele Lab, Kavli institute of nanoscience Delft)
Mark D. Jenkins (TU Delft - QN/Steele Lab, Kavli institute of nanoscience Delft)
Kenji Watanabe (National Institute for Materials Science)
Takashi Taniguchi (National Institute for Materials Science)
G.A. Steele (TU Delft - QN/Steele Lab, Kavli institute of nanoscience Delft)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Josephson junctions (JJ) are a fundamental component of microwave quantum circuits, such as tunable cavities, qubits, and parametric amplifiers. Recently developed encapsulated graphene JJs, with supercurrents extending over micron distance scales, have exciting potential applications as a new building block for quantum circuits. Despite this, the microwave performance of this technology has not been explored. Here, we demonstrate a microwave circuit based on a ballistic graphene JJ embedded in a superconducting cavity. We directly observe a gate-tunable Josephson inductance through the resonance frequency of the device and, using a detailed RF model, we extract this inductance quantitatively. We also observe the microwave losses of the device, and translate this into sub-gap resistances of the junction at μeV energy scales, not accessible in DC measurements. The microwave performance we observe here suggests that graphene Josephson junctions are a feasible platform for implementing coherent quantum circuits.