Perfect impedance matching unlocks sensitive radio-frequency reflectometry in 2D material quantum dots

TL;DR

This paper demonstrates nearly perfect impedance matching using a tunable SrTiO3 varactor to enable sensitive RF reflectometry in high-resistance 2D material quantum dots, advancing qubit readout techniques.

Contribution

It introduces the use of SrTiO3 varactors for tunable impedance matching in RF reflectometry of 2D material quantum dots, improving charge detection sensitivity.

Findings

Achieved nearly perfect impedance matching with SrTiO3 varactor.

Demonstrated clear Coulomb oscillations in RF signals.

Varactor shows robustness against magnetic fields and voltage noise.

Abstract

Two-dimensional (2D) materials are attractive platforms for realizing high-performance quantum bits (qubits). However, radio-frequency (RF) charge detection, which is a key technique for qubits readout, remains challenging in such systems. We demonstrate RF reflectometry with impedance matching for high-resistance quantum dot devices based on bilayer graphene and molybdenum disulfide. By integrating a tunable strontium titanate (SrTiO3) varactor into a resonant circuit, we achieve nearly perfect impedance matching, enabling sensitive charge detection. The demodulated RF signal clearly shows Coulomb oscillations, and the SrTiO3 varactor exhibits robustness against both magnetic fields and voltage noise on the varactor. Our results establish SrTiO3 varactors as effective tunable matching components for RF reflectometry in high-resistance 2D material quantum devices, providing a foundation for high-speed qubits readout.