Title :
1:30000 cryogenic current comparator with optimum SQUID readout
Author :
Rietveld, Gert ; Bartolomé, Elena ; Sesé, Javier ; de la Court, P. ; Flokstra, Jaap ; Rillo, Conrado ; Camón, Agustin
Author_Institution :
Dept. of Electricity & Magnetism, NMi Van Swinden Lab., Delft, Netherlands
fDate :
4/1/2003 12:00:00 AM
Abstract :
We have developed a 1:30000 winding ratio cryogenic current comparator (CCC) for measurement of small currents, e.g., generated by a single electron transport device. A dedicated low-noise SQUID is used for the readout, which allows reaching a sensitivity close to ideal, that is without loss of sensitivity in the flux transformer coupling the CCC and the SQUID. The CCC-SQUID equivalent current input noise using a 1:30 000 winding ratio is 2.1 fA/Hz12/, measured down to 0.1 Hz. Room temperature impedance measurements on CCCs appear to be a useful method for the determination of the screening by shields surrounding the CCC as well as for the detection of internal CCC resonances.
Keywords :
SQUIDs; current comparators; electric current measurement; electric impedance measurement; magnetic shielding; readout electronics; single electron devices; superconducting device noise; SQUID readout; cryogenic current comparator; current measurement; equivalent current input noise; flux transformer; impedance measurement; internal resonance; screening shield; single electron transport device; Cryogenics; Current measurement; Electrons; Impedance measurement; Noise measurement; Resonance; SQUIDs; Signal to noise ratio; Temperature measurement; Temperature sensors;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
DOI :
10.1109/TIM.2003.809916
