Trimming of critical current in niobium Josephson devices by laser annealing

摘要: The authors report a new thermal annealing technique for Nb/Al-AlOx/Nb Josephson devices based on laser heating. This allows to "locally" modify the critical current density. In fact, it is possible heating of single circuit element with good spatial resolution using focused Ar+ beam which aligned by an optical system selected junction sample. During procedure, performed at room temperature, camera provides monitoring temperature distribution whole chip. A continuous reduction density up about 40% has been observed high quality measured in liquid helium. Neighbouring junctions have not exhibited any measurable change ensuring effective capability locally employed recover noisy dc SQUID magnetometers non optimal values obtaining spectrum magnetic field noise from 30 2.5 fT/Hz1/2.