Small area, low-inductance niobium SQUID for the detection of single atomic spin-flips

We report progress towards a superconducting quantum interference device (SQUID) based system capable of detecting single atomic spin-hips. To date we have designed and had manufactured a niobium SQUID with a loop area of 3 x 10(-6) m by 3 x 10(-6) m. We present calculations which show that it is capable of detecting a few spins in a 1 Hz bandwidth, and experimental results are given which show that it operates close to the quantum-limit regime with the expected sensitivity. The SQUID is designed so that it will fit into a sample holder that will be loaded into a low-temperature ultra-high vacuum scanning tunnelling microscope (LT UHV STM). The STM will be used to image and manipulate trapped ad-atoms within the SQUID loop. (C) 2000 Published by Elsevier Science B.V. All rights reserved.