Coherent effects in series arrays of proximity effect superconducting bridges

Planar series arrays of up to 500 proximity effect superconducting bridges were fabricated with sufficient uniformity to respond coherently to incident radiation (10--20,000 MHz) without separate biasing. By varying the geometry, resistance for the arrays can range from 0.1--50 Ω. Despite this high total impedance, low frequency coherent response to external radiation is limited only by single bridge voltage noise. Low frequency (30--500 MHz) coherent internal voltage oscillations of current biased arrays were detected and confirm that the oscillating voltage signal grows linearly in bridge number while the voltage noise increases only as the square root. An array of n elements responds to incident high frequency radiation in first approximation as though it were a simple Josephson junction but quantized in units of n(h/2e). Coincident operation to high frequency depends strongly on small (less than or equal to 1μ) bridge separation. High resistance, coincident operation, and exponential dependence of critical current on temperature make these arrays good candidates for voltage standards, coherent, and bolometric radiation detectors, and cryogenic rf sources