Josephson Effects in a Bulk Granular Superconductor

Abstract

Experimental results are presented for the dc and ac Josephson effects found in a bulk granular superconductor comprised of about 10⁴ superconducting grains (less than 45 μ in dimension) packed in an insulator capsule. This new type of Josephson weakly coupled superconductor offers high sensitivity in response to microwave radiations with a noise‐equivalent power as low as 10⁻¹⁴ W/(Hz)^1/2.