Speaker
Description
Experimental search for the hypothetical axion-particle has mostly relied on linear amplification and haloscopes, where axions are assumed to convert into photons inside of a tunable resonator under high magnetic fields. As the mass of the axion is unknown, the energy spectrum to explore is large and the measurements are time consuming. Since the unavoidable quantum noise limits the sensitivity of the traditionally used linear amplification, single-photon detection is identified as a more promising sensing technology above about 10 GHz [1]. However, experiments in this mass range have been limited due to the lack of suitable detectors. As recently proposed, considerable speed-up to such experiments even at lower mass ranges may be achieved with the help of a power-meter [2]. We aim to provide suitable sensing technology for such experiments using our recently demonstrated repeatable wafer-scale fabrication platform of superconducting graphene-based Josephson field effect transistors (JoFET) [3]. Our devices rely on the superconducting proximity effect, which allows us to realize superconducting junctions with local electrostatic gate tunability. Graphene is a highly promising material for ultra-sensitive bolometers due to its low heat capacity and weak electron-phonon coupling, as demonstrated in [4]. We have used our wafer-scale methodology to fabricate graphene bolometers with various geometries and performance optimized for axion search. Currently, we are in the process of testing these sensors in our laboratory.
