Progress in Calibration of Graphene-based Josephson Junction Detector for Dark Matter Search

Graphene-based Josephson junctions have emerged as a promising platform for detecting low-energy events [1] by exploiting the exceptionally low electron heat capacity of graphene and the strong temperature dependence of the junction’s switching current. Recently, we proposed a new strategy for detecting ultra-light dark matter with masses as low as 0.1 keV using graphene-based Josephson junction detectors [2]. In this work, we introduce a detector calibration method that utilizes microwave pulses of varying amplitude for detection efficiency and dark count probability. This calibration technique enables the precise determination of the mass range of dark matter that the detector can detect. In addition, the thermal relaxation time of graphene was also quantitatively analyzed with the two-pulse experiment. This provides information on thermal properties of graphene at low-temperature, which is valuable for optimizing detector performance.

[1] G.-H. Lee, Nature 586, 42 (2020);R. Kokkoniemi, Nature 586, 47 (2020).

[2] D. Kim, arXiv:2002.07821v3 [hep-ph].