Macroscopic quantum electrodynamic effects in a superconducting ring containing a Josephson weak link

Abstract

The problem of coherent flux tunnelling across a Josephson weak link enclosed by a thick superconducting (‘SQUID‘) ring in terms of quantum electrodynamics is considered. We show that for a low effective noise temperature (≃few K) in the SQUID ring and with the weak link capacitance ≲3 × 10−15, such a process should be observable. Experimental evidence is given to justify this claim.