Novel DC Micro Squid
Original Publication Date: 1979-Jun-01
Included in the Prior Art Database: 2005-Feb-20
The DC SQUID (superconducting quantum interference device) is generally conceived as a superconducting loop containing two Josephson junctions. A magnetic flux applied to the device induces a circulating current in the loop which modulates the critical current of the two junctions. The critical current is a periodic function of the applied magnetic flux with the period equal to the flux quantum. In the usual mode of operation the DC SQUID is used as the null detector in a feedback circuit to measure a small fraction of a flux quantum. An example of a DC SQUID is shown in Fig. 1. Such a SQUID contains two superconducting loops and is sensitive only to the difference in flux in the two loops (gradiometer). Cutting one of the loops produces a magnetometer.