On-chip integrable planar NbN nanoSQUID with broad temperature and magnetic-field operation range

Abstract

Superconducting quantum interference devices (SQUIDs) are used for applications ranging from sensitive magnetometers to low-temperature electronics and quantum computation. Miniaturizing SQUIDs is technologically attractive for increasing spin sensitivity as well as device integration and circuit speed. We introduce a planar nano SQUID that was made with a single lithographic step out of NbN films as thin as 3 nm on a Si chip. The fabrication process of weak links that are 45 nm in width, and 165 nm in length, which were designed to account for overcoming current crowding are presented. Operation at a temperature range of 20 mK to 5 K as well as at 1 T parallel, and 10 mT perpendicular magnetic fields is demonstrated, while potential operation higher than 8 T has also been shown. The broad range of applicability of a single device as well as its scalability are promising for on-chip integrability that may open technological possibilities, including in quantum and electro-optical circuiting.