Phys.org January 8, 2018
The ability to develop SQUID-based quantum computers will require the stored magnetic data survive for long times. Theory calculations by a team of researchers in the US (University of Wisconsin–Madison, Argonne National Laboratory, UC Irvine, NIST-Colorado), showed that adsorbed molecular oxygen on the surfaces is the dominant contributor to magnetic noise for superconducting niobium and aluminum thin films. They found that surface treatment with ammonia and improving the sample vacuum environment dramatically reduced the surface contamination (to less than one oxygen molecule per 10 nm2), minimizing magnetic noise. Their work provides a design strategy for the development of tunable superconducting qubits with long lifetimes. It could lead to frequency-tunable superconducting qubits with improved dephasing times for practical quantum computers… read more TECHNICAL ARTICLE 1, 2
The sketch shows twisted magnetic field lines induced by harmful fluctuating magnetic spins (arrows) of O2 (spheres) on the surface of a SQUID quantum bit. Credit: US Department of Energy