Rapid high-fidelity gate-based spin read-out in silicon

TL;DR

This paper demonstrates rapid, high-fidelity, on-chip gate-based spin read-out in silicon quantum dots, significantly reducing measurement time and enabling scalable quantum computing architectures.

Contribution

The authors introduce an on-chip superconducting resonant circuit for spin read-out, achieving single-shot measurements with over 98% fidelity in 6 microseconds, surpassing previous methods.

Findings

Achieved a signal-to-noise ratio of about six within 1 microsecond.

Demonstrated single-shot spin state read-out with >98% fidelity in 6 microseconds.

Enabled frequency multiplexed read-out without external electrometers.

Abstract

Silicon spin qubits form one of the leading platforms for quantum computation. As with any qubit implementation, a crucial requirement is the ability to measure individual quantum states rapidly and with high fidelity. As the signal from a single electron spin is minute, different spin states are converted to different charge states. Charge detection so far mostly relied on external electrometers, which hinders scaling to two-dimensional spin qubit arrays. As an alternative, gate-based dispersive read-out based on off-chip lumped element resonators were introduced, but here integration times of 0.2 to 2 ms were required to achieve single-shot read-out. Here we connect an on-chip superconducting resonant circuit to two of the gates that confine electrons in a double quantum dot. Measurement of the power transmitted through a feedline coupled to the resonator probes the charge susceptibility, distinguishing whether or not an electron can oscillate between the dots in response to the probe power. With this approach, we achieve a signal-to-noise ratio (SNR) of about six within an integration time of only 1 $\mu$s. Using Pauli's exclusion principle for spin-to-charge conversion, we demonstrate single-shot read-out of a two-electron spin state with an average fidelity of $>$98% in 6 $\mu$s. This result may form the basis of frequency multiplexed read-out in dense spin qubit systems without external electrometers, therefore simplifying the system architecture.