Sensitive radiofrequency readout of quantum dots using an ultra-low-noise SQUID amplifier
Measuring the sate of qubits in a short time is crucial to building a scalable quantum computer.
In this article, F. Schupp, F. Vigneau, Y. Wen, G.A.D. Briggs, N. Ares, E.A. Laird and co-authors introduce a superconducting quantum interference amplifier to measure more efficiently qubits in quantum dots and other quantum devices. This gives more than a tenfold improvement, with a noise temperature below 600 mK, enabling them to detect a change in capacitance as little as 0.07 aF/√Hz.
The figure shows the charge stability diagram of a gate-defined double quantum dot; SNR = 38 measured at 1µs/data point.