Josephson-inductive readout of graphene bolometer

Ultrafast microwave bolometers that can detect radiation down to the single photon regime are a key technology for developing quantum sensors for radio-astronomy, as well as quantum information processing. While there have been a few demonstrations of microwave single photon detection using superconducting transmon qubits coupled to a cavity, the challenge still remains of how one can best detect and read out single photons across a spectrum of microwave frequencies. In this regard, graphene is an excellent material for microwave sensors; it has an extremely small heat capacity and broadband absorption spectrum. Extending our previous work on graphene-based microwave bolometers [1], we have developed an inductive readout technique that reads out changes in the electronic temperature of the Josephson junction (JJ) weak link. Our technique is able to detect broadband microwave radiation between 10 GHz and 13 GHz, limited only by the bandwidth of the input resonator. Discussions of the operating principles of our readout scheme and ways to improve the NEP will be further discussed in this talk.

[1] “Graphene-based Josephson junction microwave bolometer,” Lee, G. H., et al., Nature 586, 42-46 (2020).