Full capacitance matrix effects in driven underdamped Josephson junction arrays

Y. Yoon, Simone Gasparinetti, Mikko Möttönen +1 more

Zlatko Minev, Ioan M. Pop, Nicholas A. Masluk +2 more

Makoto R. Arai, Vinay Ambegaokar

Amy Duwel, Herre S. J. van der Zant, Terry P. Orlando

Vortex flow devices consisting of discrete arrays of underdamped Josephson junctions have been fabricated and measured. These devices and their long, continuous junction counterparts are based on the ability to magnetically control the Eck voltage in an underdamped system. We find that both transistor and oscillator parameters are improved by placing the arrays above a superconducting ground plane and by connecting two arrays in series. We developed models for the device behavior which numerically account for the measured parameters. Our models also suggest that junctions with smaller capacitances will further improve the device parameters.>

D. Massarotti, Luigi Longobardi, D. Stornaiuolo +5 more

Herre S. J. van der Zant, R. A. M. Receveur, Terry P. Orlando +1 more

We propose and demonstrate the use of underdamped, one-dimensional parallel arrays of Josephson junctions as a tool for circuit diagnostics. By measuring the Fiske modes and the critical current in a magnetic field, we determined the self- and nearest-neighbor inductances as well as the capacitances of single junctions. We have used this technique to find the capacitance of Nb-Al2Ox-Nb junctions for critical current densities of 0.3–20 kA/cm2. We find that the specific capacitance increases by about a factor of 2 over this range. This increase has important consequences for the design of single-flux-quantum circuits and SQUIDs. Measurement of the junction capacitance for critical current densities of 100 kA/cm2 is possible, but requires submicrometer junctions with dimensions of the order of 0.3 μm.