2015/10/05 by Quentin Herr, Herr, Quentin P., J. Osborne +15
Physics and Astronomy · Engineering · #Physics of Superconductivity and Magnetism #Advanced Electrical Measurement Techniques #Quantum and electron transport phenomena
paper · pdf · doi:10.48550/arxiv.1510.01220
We report the design and test of Reciprocal Quantum Logic shift-register\nyield vehicles consisting of up to 72,800 Josephson junction devices per die,\nthe largest digital superconducting circuits ever reported. Multiple physical\nlayout styles were matched to the MIT Lincoln Laboratory foundry, which\nsupports processes with both four and eight metal layers and minimum feature\nsize of 0.5 \μm. The largest individual circuits with 40,400 junctions\nindicate large operating margins of \±20% on AC clock amplitude. In one case\nthe data were reproducible to the accuracy of the measurement, \±1% across\nfive thermal cycles using only the rudimentary precautions of passive mu-metal\nmagnetic shielding and a controlled cool-down rate of 3 mK/s in the test\nfixture. We conclude that with proper mitigation techniques, flux-trapping is\nno longer a limiting consideration for very-large-scale-integration of\nsuperconductor digital logic.\n