| 摘要 |
PCT No. PCT/US93/08496 Sec. 371 Date Mar. 17, 1995 Sec. 102(e) Date Mar. 17, 1995 PCT Filed Sep. 7, 1993 PCT Pub. No. WO95/07470 PCT Pub. Date Mar. 16, 1995A coupling structure for coupling a feedback signal to a superconducting quantum interference device (SQUID) by mutual inductance. In one embodiment the SQUID loop (A) is shielded from external magnetic fields perpendicular to it by a superconducting ground plane (B) at all points except for the pick-up loop (C). A feedback signal is coupled to the SQUID loop (A) by a feedback loop (D) which has a mutual inductance with the SQUID loop (A). During operation, the feedback loop (D) conducts a current in only one direction around the SQUID loop (A). This geometry ensures that the SQUID loop (A) is shielded from external magnetic fields, except at the pick-up loop (C), by the ground plane, and is balanced against fields parallel to the ground plane. The magnetic field produced by the current in the feedback coil (D) is small far from the SQUID (A). The feedback loop (D) is connected to exterior feedback electronics.
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