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Investigating the Intrinsic Noise Limit of Dayem Bridge NanoSQUIDs

Patel, T; Li, B; Gallop, L; Cox, D; Kirby, K; Romans, EJ; Chen, J; ... Hao, L; + view all (2015) Investigating the Intrinsic Noise Limit of Dayem Bridge NanoSQUIDs. IEEE Transactions on Applied Superconductivity , 25 (3) , Article 1602105. 10.1109/TASC.2014.2364920. Green open access

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NanoSQUIDs made from Nb thin films have been produced with nanometre loop sizes down to 200 nm, using weak-link junctions with dimensions less than 60 nm. These composite (W/Nb) single layer thin film devices, patterned by FIB milling, show extremely good low-noise performance ~170 nΦo at temperatures between 5 and 8.5 K and can operate in rather high magnetic fields (at least up to 1 T) . The devices produced so far have a limited operating temperature range, typically only 1-2 K. We have the goal of achieving operation at 4.2 K, to be compatible with the best SQUID series array (SSA) preamplifier available. Using the SSA to readout the nanoSQUIDs provides us with a means of investigating the intrinsic noise of the former. In this paper we report improved white noise levels of these nanoSQUIDs, enabling potential detection of a single electronic spin flip in a 1-Hz bandwidth. At low frequencies the noise performance is already limited by SSA preamplifier noise.

Type: Article
Title: Investigating the Intrinsic Noise Limit of Dayem Bridge NanoSQUIDs
Open access status: An open access version is available from UCL Discovery
DOI: 10.1109/TASC.2014.2364920
Publisher version: https://doi.org/10.1109/TASC.2014.2364920
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: NanoSQUIDs, noise measurements, Tc suppression, SQUIDs, Noise, Junctions, Critical current density (superconductivity), Nanoscale devices, Preamplifiers, Niobium
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng
URI: https://discovery.ucl.ac.uk/id/eprint/1455271
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