Low Temperature Radiofrequency Reflectometry setup for Charge sensing in CMOS devices

Spin qubits in silicon are great candidates for scalable quantum information processors due to their long coherence time combined with compatibility with industrial CMOS fabrication lines [1]. The spin-readout is obtained by spin-to-charge conversion using a nearby SET. This require multiple additional leads and limits the scalability of the system. RF-reflectometry measurement provides a compact alternative [2,3] as only one lead is necessary to control and read the qubit [4]. The critical part for this measurement is to obtain an impedance matching, at low temperature, between the resonant circuit and the RF-line. This is due to the temperature dependence of each of the tank circuit components and the sample-to-sample capacitance variability. In this talk, we report a charge-sensing measurement of a CMOS device with optimized reflectometry setup and discuss the use of tunable capacitors to target high sensitivity RF-measurement for spin qubit readout.

[1] M. Veldhorst, et al., Nat. Nano. 9, 981–985 (2014)
[2] B. J. Villis, et al., Appl. Phys. Lett. 104, 233503 (2014)
[3] I. Ahmed, et al., Appl. Phys. Lett. 10, 014018 (2018)
[4] P. Pakkiam, et al., Phys. Rev., 8, 041032 (2018)