Low-noise symmetric dc SQUID system having two pairs of washer coils and a pair of Josephson junctions connected in series
US5656937A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 7, 1995 |
| Grant date | Aug 12, 1997 |
| Priority date | — |
| Expiry date | Jun 7, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S505/846
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A multiple loop dc SQUID configuration with input and modulation circuitry configured for high-symmetry and low-noise operation is disclosed. The configuration is adaptable to implementation using standard thin film circuit fabrication technology. The SQUID inductance is defined by a plurality of washer-shaped thin superconducting films symmetrically oriented on a substrate and connected in series through a pair of Josephson junctions to form a multiple-washer gradiometric structure. The series connection arrangement also minimizes the number of required input and output terminal pads. Bias and modulation conductors are configured so as to prevent magnetic fields produced by currents flowing therethrough from coupling to the SQUID, and the modulation and input coil portions of the SQUID circuit are symmetrically configured to minimize signal coupling therebetween. A method of parameter selection for the input and modulation circuit portions of the SQUID configuration is disclosed which establishes a well-defined resonance point for the SQUID, within which low-noise operation is possible.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.