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Browse Prior Art Database

Light Triggered Superconducting Current Switches

IP.com Disclosure Number: IPCOM000050014D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 35K

Publishing Venue

IBM

Related People

Faris, SM: AUTHOR [+3]

Abstract

This article relates generally to Josephson junction devices and more particularly to light triggered superconducting switches. The article shows how superconducting strips may be used as switches and how auto-correlation can be used to measure device-switching speed.

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Light Triggered Superconducting Current Switches

This article relates generally to Josephson junction devices and more particularly to light triggered superconducting switches. The article shows how superconducting strips may be used as switches and how auto-correlation can be used to measure device-switching speed.

Figs. 1 and 2 show different current switching schemes for introducing optical information into the superconducting environment.

Referring to the circuit shown in Fig. 1, a supercurrent i(g) can follow two paths, p1 and p2, in a superconductive material. Path p2 has high inductance relative to p1. Optical fibers are placed directly above paths p1 and p2 so that light exiting from the fibers illuminates regions S1 and S2, as shown in Fig. 1. At time zero, with regions S1 and S2 nonilluminated (off), it is assumed that i(1) approximately equals i(g) and i(2) approximately equals 0. This is possible because of the high inductance of p2 relative to p1. When S1 is illuminated (turned-on), path p1 becomes resistive and current i(g) switches to P2 (i(1) approximately equals 0 and i(2) approximately equals i(g), triggering the Josephson device(s). When S1 is turned-off, the resistance disappears within a nanosecond but the initial current in path p1 is not re-established. When S2 turns-on, i(2) goes to zero and i(1) approximately equals i(g). When S2 turns-off, this condition is retained. Since the pulses used are likely to be derived from the same source (use a beam splitter and optical delay), it is a simple matter to let the pulses overlap in time. In this instance, the switched state on-time is determined by the relative delay between the pulses. It is obvious, of course, that this light-induced resistive effect can be used as a variable voltage source controlled by the light intensity I.

In the circuit show...