The dc SQUID near the quantum noise limit
Abstract
A series of dc SQUIDs has been fabricated in an attempt to obtain quantumlimited sensitivity. Typically, the SQUID inductance, L, is 2 pH, the capacitance and critical current of each tunnel junction are 0.5 pF and 0.5 mA, and the shunt resistance for each junction is 1 ohm. The measured spectral density of the voltage noise S/sub v/ contains a 1/f component that extends typically to 100 kHz or higher. When the 1/f component is substracted out, the best energy sensitivity achieved to date is epsilon/1Hz  S/sub v// 2L(delta V/delta PHI)squared less than or approximately equal to 2h, where delta V/delta PHI is the transfer coefficient.
 Publication:

Presented at the 16th Intern. Conf. on Low Temperature Phys
 Pub Date:
 1981
 Bibcode:
 1981ltp..confR..19V
 Keywords:

 Squid (Detectors);
 Tunnel Diodes;
 White Noise;
 Capacitance;
 Inductance;
 Quantum Counters;
 Semiconductor Junctions;
 Sensitivity;
 Electronics and Electrical Engineering