Radio frequency reflectometry in semiconductor-superconductor hybrid systems

Radio frequency (RF) reflectometry is a useful tool to perform fast measurements in various mesoscopic systems [1]. Resonators can be attached to normal leads or the gates of a device [2] to read out different physical quantities. Here we study two quantum dots coupled by a semiconductor-superconductor hybrid region in a two-dimensional electron gas, using both lead reflectometry and gate reflectometry. When the system is connected to the leads, we find that both gate sensing and lead sensing can be used to detect the type of coupling between quantum dots. When the system is isolated from normal leads, gate sensing can be used to detect the parity of the system. Furthermore, we find that gate sensing can also be used to study the coupling between a single quantum dot and Andreev bound states in the hybrid region. The ability to probe interdot couplings in the absence of normal leads could be beneficial for the study of more complex systems, such as long Kitaev chains.

[1] Vigneau F, Fedele F, Chatterjee A, et al. Probing quantum devices with radio-frequency reflectometry[J]. Applied Physics Reviews, 2023, 10(2).

[2] de Jong D, Prosko C G, Han L, et al. Controllable single Cooper pair splitting in hybrid quantum dot systems[J]. Physical review letters, 2023, 131(15): 157001.