Fast high-fidelity single-shot readout of spins in silicon using a single-electron box

TL;DR

This paper demonstrates a fast, high-fidelity, single-shot spin readout in silicon quantum dots using a compact dispersive charge sensor, achieving 99.2% fidelity in under 6 microseconds, advancing scalable quantum processor readout technology.

Contribution

The authors introduce a novel, compact dispersive charge sensor for spin readout in silicon quantum dots, achieving state-of-the-art speed and fidelity with fewer electrodes.

Findings

Achieved 99.2% spin readout fidelity in less than 6 μs.

Used low-loss high-impedance resonators with Josephson parametric amplification.

Showed the effectiveness of Pauli spin blockade for spin-to-charge conversion.

Abstract

Three key metrics for readout systems in quantum processors are measurement speed, fidelity and footprint. Fast high-fidelity readout enables mid-circuit measurements, a necessary feature for many dynamic algorithms and quantum error correction, while a small footprint facilitates the design of scalable, highly-connected architectures with the associated increase in computing performance. Here, we present two complementary demonstrations of fast high-fidelity single-shot readout of spins in silicon quantum dots using a compact, dispersive charge sensor: a radio-frequency single-electron box. The sensor, despite requiring fewer electrodes than conventional detectors, performs at the state-of-the-art achieving spin read-out fidelity of 99.2% in less than 6 $\mu$s. We demonstrate that low-loss high-impedance resonators, highly coupled to the sensing dot, in conjunction with Josephson parametric amplification are instrumental in achieving optimal performance. We quantify the benefit of Pauli spin blockade over spin-dependent tunneling to a reservoir, as the spin-to-charge conversion mechanism in these readout schemes. Our results place dispersive charge sensing at the forefront of readout methodologies for scalable semiconductor spin-based quantum processors.