Measurement and noise performance of nano-superconducting-quantum-interference devices fabricated by focused ion beam

Science and industry demand ever more sensitive measurements on ever smaller systems, as exemplified by spintronics, nanoelectromechanical system, and spin-based quantum information processing, where single electronic spin detection poses a grand challenge. Superconducting quantum interference devices (SQUIDs) have yet to be effectively applied to nanoscale measurements. Here, we show that a simple bilayer deposition route, combining photolithography with focused ion beam patterning, produces high performance nanoscale SQUIDs. We present results of noise measurements on these nanoSQUIDs which correspond to a magnetic flux sensitivity of around 0.2 μ Φ 0 ∕ Hz 1 ∕ 2 . This represents one of the lowest noise values achieved for a SQUID device operating above 1 K .