Recent studies of silicon spin qubits at temperatures above 1 K are encouraging demonstrations that the cooling requirements for solid-state quantum computing can be considerably relaxed. However, qubit readout mechanisms that rely on charge sensing with a single-island single-electron transistor (SISET) quickly lose sensitivity due to thermal broadening of the electron distribution in the reservoirs. Here we exploit the tunneling between two quantised states in a double-island SET (DISET) to demonstrate a charge sensor with an improvement in signal-to-noise by an order of magnitude compared to a standard SISET, and a single-shot charge readout fidelity above 99 % up to 8 K at a bandwidth > 100 kHz. These improvements are consistent with our theoretical modelling of the temperature-dependent current transport for both types of SETs. With minor additional hardware overheads, these sensors can be integrated into existing qubit architectures for high fidelity charge readout at few-kelvin temperatures.
@article{arxiv.2103.06433,
title = {A high-sensitivity charge sensor for silicon qubits above one kelvin},
author = {Jonathan Y. Huang and Wee Han Lim and Ross C. C. Leon and Chih Hwan Yang and Fay E. Hudson and Christopher C. Escott and Andre Saraiva and Andrew S. Dzurak and Arne Laucht},
journal= {arXiv preprint arXiv:2103.06433},
year = {2021}
}