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)