RF SQUID in the nonhysteretic regime with k/sup 2/Ql>1

Journal Article · Wed Dec 01 04:00:00 EST 1982 · J. Low Temp. Phys.; (United States)

DOI:https://doi.org/10.1007/BF00681894· OSTI ID:6336471

Dmitrenko, I M; Tsoi, G M; Shnyrkov, V I; Kartsovnik, V V

Experimental measurements of current-voltage, current-phase, amplitude-frequency, phase-frequency, and signal characteristics of an rf SQUID operating at a frequency of 30 MHz in the nonhysteretic regime (1 = 2..pi..L/sub 0/I/sub 0//phi/sub o/<1) were carried out for the condition k/sup 2/Ql>1. Here I/sub 0/ is the critical current of the weak link, L/sub 0/ is the SQUID ring inductance, k is the coefficient of coupling of the SQUID ring to a resonant tank circuit of quality Q, and phi/sub 0/ is the magnetic flux quantum. A numerical analysis of the above characteristics for all relevant parameter values close to those occurring under experimental conditions was performed for qualitative comparison with theory. The main difference from the traditional nonhysteretic regime of SQUID operation (k/sup 2/Q1<1, l<1) is the possibility of a strong increase in the magnetic flux-to-voltage transfer coefficients eta/sub a/ and eta/sub theta/ corresponding to changes in the rf amplitude and the phase. The increase in eta is known to reduce the amplifier noise contribution to the SQUID energy resolution. At a temperature of 4.2 K the maximum value of the transfer coefficient was estimated experimentally as eta = (3 +- 2) x 10/sup 12/ V/Wb for the single-valued region of the signal characteristics. The results suggest that considerable improvement of rf SQUID resolution is possible in the regime k/sup 2/Ql>1.

• Research Organization: Physico-Technical Institute of Low Temperatures of the Academy of Sciences of the Ukraine, Kharkov, USSR
• OSTI ID: 6336471
• Journal Information: J. Low Temp. Phys.; (United States), Journal Name: J. Low Temp. Phys.; (United States) Vol. 49:5; ISSN JLTPA
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment &amp; Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ELECTRIC CONDUCTIVITY
ELECTRIC POTENTIAL
ELECTRICAL PROPERTIES
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUXMETERS
FREQUENCY RANGE
MAGNETIC FLUX
MEASURING INSTRUMENTS
MHZ RANGE
MHZ RANGE 01-100
MICROWAVE EQUIPMENT
NOISE
PHYSICAL PROPERTIES
SIGNALS
SQUID DEVICES
SUPERCONDUCTING DEVICES