Radio-Frequency-Detected Fast Charge Sensing in Undoped Silicon Quantum Dots
journal contributionposted on 2020-01-23, 18:04 authored by Akito Noiri, Kenta Takeda, Jun Yoneda, Takashi Nakajima, Tetsuo Kodera, Seigo Tarucha
Spin qubits in silicon quantum dots offer a promising platform for a quantum computer as they have a long coherence time and scalability. The charge sensing technique plays an essential role in reading out the spin qubit as well as tuning the device parameters, and therefore, its performance in terms of measurement bandwidth and sensitivity is an important factor in spin qubit experiments. Here we demonstrate fast and sensitive charge sensing by radio frequency reflectometry of an undoped, accumulation-mode Si/SiGe double quantum dot. We show that the large parasitic capacitance in typical accumulation-mode gate geometries impedes reflectometry measurements. We present a gate geometry that significantly reduces the parasitic capacitance and enables fast single-shot readout. The technique allows us to distinguish between the singly- and doubly occupied two-electron states under the Pauli spin blockade condition in an integration time of 0.8 μs, the shortest value ever reported in silicon, by the signal-to-noise ratio of 6. These results provide a guideline for designing silicon spin qubit devices suitable for the fast and high-fidelity readout.
gate geometryradio frequency reflectometryqubit devicestwo-electron statesdevice parametersRadio-Frequency-Detected Fast ChargeUndoped Silicon Quantum Dots Spin qubitscapacitanceaccumulation-mode gate geometrieshigh-fidelity readouttechniquechargequantum computerqubit experimentsquantum dotcoherence time0.8 μblockade conditionsilicon quantum dots offermeasurement bandwidthreflectometry measurementsintegration time