The horizon of Josephson point contacts

Josephson point contacts can have rather small dynamic capacitances of orde r 0.1 fF and huge plasma frequencies omega(p) greater than or equal to 1 ps (-1). The quantum-mechanical zero-point fluctuations of the Josephson plasm a interact with the electromagnetic held only inside the horizon similar to c/omega, of the junction, and the dynamic capacitance turns out to be C ap proximate to kappa c/omega(p) at a lead capacitance per length kappa. Those contacts can easily resist external high-frequency noise. (C) 2000 Elsevie r Science B.V. All rights reserved.