Radio-frequency response of a graphene Josephson junction based superconducting oscillator circuit*

Recent experimental realizations on Superconductor-Normal-Superconductor (SNS) junctions provide a platform to study gate tunable Josephson junctions (JJ), where one can tune the junction properties like critical current by means of electrostatic gating in a field-effect transistor (FET) based device geometry. Because of the non-linear inductive nature of JJs at finite frequencies, the SNS junctions are potential candidates to be used in gate tunable resonators in circuit QED experiments. Such resonators can have a variety of applications like - superconducting Qubits, low-noise amplifiers, high-sensitive radiation detectors, etc. The ability to tune JJ inductance with electrostatic gating gives freedom in frequency biasing at a desirable frequency window. We report graphene JJ-based LC oscillators which are promising candidates for low-noise RF signal amplifiers. We implement MoRe-Graphene-MoRe junctions as the gate tunable JJs. The nature of the JJ non-linearity is vital for such applications. Hence such measurements can also provide information about the current phase relationship (CPR) and nature of non-linearity in SNS JJs which is supposed to be different from known sinusoidal CPR in Superconductor-Insulator-Superconductor (SIS) junctions.