Splitting individual Cooper pairs and single photon detection in superconducting aluminium

Using superconducting aluminum quantum dots, we demonstrate the splitting of individual Cooper pairs using microwave light [1]. Within our nanoscale devices, the competition at low temperatures between the charging energy, superconducting gap and Josephson energy enables single Cooper pairs to be split and reformed. The delivery of constituent quasi-particles to separate quantum dots has facilitated measurements of both splitting and recombination. The devices are probed by radio-frequency reflectometry, a technique sensitive to the `quantum capacitance' of the device band structure [2]. We intentionally induce splitting via the application of a microwave field, indicating a system able to detect individual photons of microwave light [1]. To controllably separate a Cooper pair into two quasi-particles may have important implications for quantum information processing; future experiments will investigate the coupling of a double quantum dot to a microwave resonator for single photon detection [3], with applications to circuit quantum electrodynamics. \\[4pt] [1] N. J. Lambert \textit{et al}., Phys. Rev. B., 90, 140503(R), 2014\\[0pt] [2] T. Duty \textit{et al.}, Phys. Rev. Lett., 95, 206807, 2005\\[0pt] [3] M. G\"{o}ppl \textit{et al.}, J. Appl. Phys., 104, 113904, 2008