Design of a Cooper-Pair Box Electrometer for Application to Solid-State and Astroparticle Physics

The authors design a single-charge electrometer with sensitivity improved by an order of magnitude, compared to the state of the art. This improvement is obtained by taking full advantage of the quantum nature of the measuring circuit. Importantly, such an electrometer could improve by one or two orders of magnitude the sensitivity of astroparticle experiments such as bolometric direct dark-matter detection, or coherent neutrino scattering. This quantum sensor is also potentially useful in mesoscopic physics, in particular to unveil the physics of Majorana fermions.