Rights statement: Copyright 2020 American Institute of Physics. The following article appeared in Journal of Applied Physics, 127, 24 2020 and may be found at http://dx.doi.org/10.1063/5.0005886 This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
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Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
| Article number | 0005886 |
|---|---|
| <mark>Journal publication date</mark> | 28/06/2020 |
| <mark>Journal</mark> | Journal of Applied Physics |
| Issue number | 24 |
| Volume | 127 |
| Number of pages | 9 |
| Publication Status | Published |
| <mark>Original language</mark> | English |
Fault-tolerant spin-based quantum computers will require fast and accurate qubit read out. This can be achieved using radiofrequency reflectometry given sufficient sensitivity to the change in quantum capacitance associated with the qubit states. Here, we demonstrate a 23-fold improvement in capacitance sensitivity by supplementing a cryogenic semiconductor amplifier with a SQUID preamplifier. The SQUID amplifier operates at a frequency near 200MHz and achieves a noise temperature below 600mK when integrated into a reflectometry circuit, which is within a factor 120 of the quantum limit. It enables a record sensitivity to capacitance of
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