Noise in dc SQUIDs with Nb/Al-oxide/Nb Josephson junctions
Abstract
The authors have developed a process which incorporates very-high-quality Nb/Al-oxide/Nb Josephson junctions. The junctions had low subgap conductance, yielding Vm greater than 50 mV for critical current densities of 1000 A/sq cm. Low-inductance SQUIDs (superconducting quantum interference devices) made with these junctions were apparently free from junction conductance fluctuations, at least for frequencies above 1 Hz. A correlation between low leakage junctions and low noise from critical current fluctuations was observed. The SQUIDs exhibited flux noise with an unusual frequency dependence of currently unknown origin.
- Publication:
-
IEEE Transactions on Magnetics
- Pub Date:
- March 1989
- DOI:
- 10.1109/20.92458
- Bibcode:
- 1989ITM....25.1005C
- Keywords:
-
- Current Density;
- Josephson Junctions;
- Niobium;
- Noise Measurement;
- Squid (Detectors);
- Volt-Ampere Characteristics;
- Aluminum Oxides;
- Low Noise;
- Plasma Etching;
- Transfer Functions;
- Electronics and Electrical Engineering