  We introduce the concept of Berry's phase in Josephson junctions and consider
how this geometric phase arises due to applied oscillating electric fields. The
electromagnetic field excites topological quasi-particles from the junction
vacuum which affect Cooper-pair tunneling across the Josephson junction
barrier. A finite Berry's phase can be detected by its renormalization of the
electric field amplitude absorbed by the junction. This has implications for
the designing of accurate Josephson junction microwave detectors.
