The diamond superconducting quantum interference device.

Diamond is an electrical insulator in its natural form. However, when doped with boron above a critical level (∼0.25 atom %) it can be rendered superconducting at low temperatures with high critical fields. Here we present the realization of a micrometer-scale superconducting quantum interference device (µ-SQUID) made from nanocrystalline boron-doped diamond (BDD) films. Our results demonstrate that µ-SQUIDs made from superconducting diamond can be operated in magnetic fields as large as 4 T independent of the field direction. This is a decisive step toward the detection of quantum motion in a diamond-based nanomechanical oscillator.

Efficient radio frequency filters for space constrained cryogenic setups.

Noise filtering is an essential part for measurement of quantum phenomena at extremely low temperatures. Here, we present the design of a filter which can be installed in space constrained cryogenic environment containing a large number of signal carrying lines. Our filters have a -3 db point of 65 kHz and their performance at GHz frequencies is comparable to the best available RF filters.