Dispersive readout of a silicon quantum device using an atomic force microscope-based rf gate sensor

We demonstrate dispersive charge sensing of Si/SiGe single and double quantum dots by coupling sub-micron floating gates to a radio frequency reflectometry (rf-reflectometry) circuit using the tip an atomic force microscope. Charge stability diagrams are obtained in phase response reflected rf signal. single-electron dot-to-lead dot-to-dot transitions with signal-to-noise ratio (SNR) 2 integration time τ=2.7 ms τ=6.4 ms, respectively. The SNR compares favorably results on conventional devices. Moreover, small size largely eliminates parasitic traps that can complicate interpretation data.