Characteristics of Josephson Point Contacts at the Center of a Spherical Cavity
We report the measurement of the characteristics of superconducting Nb—Nb point contacts located at the center of a spherical cavity of large diameter compared to the wavelength of Josephson radiation in the millivolt range of interest. In this range the cavity could reasonably be expected to behave as a broadband mirror (or equivalently a cavity operating in a high mode) which provides “optical feedback.” Since the center of the cavity is a perfect optical focus, it would appear that any radiation leaving the point–contact region would be returned there “in focus” with a wavelength–dependent phase shift. In principle, by comparing measurements made with or without the cavity something could be learned about the explicit effects of optical feedback on the tunneling currents as well as on the emission and detection properties.
KeywordsPoint Contact Spherical Cavity Optical Feedback Explicit Effect Point Adjustment
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