Difficult to say this problem is solved yet - the jury is still out, but I've done a good deal of work on identifying what the mechanism of a defect in supercon

Difficult to say this problem is solved yet - the jury is still out, but I've done a good deal of work on identifying what the mechanism of a defect in superconducting phase qubits may be. TL;DR: Two level system defects are a 20 year old unidentified noise source that can be described by an oxygen spatially delocalising in an amorphous portion of the underlying circuit. See http://dx.doi.org/10.1103/PhysRevLett.110.077002 http://dx.doi.org/10.1103/PhysRevLett.110.077002 and http://dx.doi.org/10.1088/1367-2630/17/2/023017 http://dx.doi.org/10.1088/1367-2630/17/2/023017.