A Numerical Treatment of the Rf SQUID: I. General Properties andNoise Energy
We investigate the characteristics and noise performance of rf Superconducting Quantum Interference Devices (SQUIDs) by solving the corresponding Langevin equations numerically and optimizing the model parameters with respect to noise energy. After introducing the basic concepts of the numerical simulations, we give a detailed discussion of the performance of the SQUID as a function of all relevant parameters. The best performance is obtained in the crossover region between the dispersive and dissipative regimes, characterized by an inductance parameter {beta}{prime}{sub L} {triple_bond} 2{pi}LI{sub 0}/{Phi}{sub 0} {approx} 1; L is the loop inductance, I{sub 0} the critical current of the Josephson junction, and {phi}{sub 0} the flux quantum. In this regime, which is not well explored by previous analytical approaches, the lowest (intrinsic) values of noise energy are a factor of about 2 above previous estimates based on analytical approaches. However, several other analytical predictions, such as the inverse proportionality of the noise energy on the tank circuit quality factor and the square of the coupling coefficient between the tank circuit and the SQUID loop, could not be well reproduced. The optimized intrinsic noise energy of the rf SQUID is superior to that of the dc SQUID at all temperatures. Although for technologically achievable parameters this advantage shrinks, particularly at low thermal fluctuation levels, we give an example for realistic parameters that leads to a noise energy comparable to that of the dc SQUID even in this regime.
- Research Organization:
- COLLABORATION - U.Tubingen/Germany
- Sponsoring Organization:
- USDOE Director. Office of Science. Basic EnergySciences
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 928013
- Report Number(s):
- LBNL-62298-(I); JLTPAC; R&D Project: 504801; BnR: KC0202020; TRN: US0804689
- Journal Information:
- Journal of Low Temperature Physics, Vol. 149, Issue 5-6; Related Information: Journal Publication Date: 12/2007; ISSN 0022-2291
- Country of Publication:
- United States
- Language:
- English
Similar Records
RF SQUID in the nonhysteretic regime with k/sup 2/Ql>1
Influence of the tank circuit on the low frequency impedance of an rf-biased R-SQUID