Low noise multiwasher superconducting interferometer
作者:
P. Carelli,
M. G. Castellano,
G. Torrioli,
R. Leoni,
期刊:
Applied Physics Letters
(AIP Available online 1998)
卷期:
Volume 72,
issue 1
页码: 115-117
ISSN:0003-6951
年代: 1998
DOI:10.1063/1.121444
出版商: AIP
数据来源: AIP
摘要:
The dc-superconducting quantum interference device (SQUID) is a low-noise converter from magnetic flux to voltage which can have, in principle, an energy sensitivity near the quantum limit ofℏ/2.A critical parameter for the ideal performance is the device inductance, which must be kept as small as possible. Minimizing the SQUID inductance, however, is a major concern for a practical device; this requirement implies a small SQUID ring and hence magnetic coupling with an external signal is more difficult to achieve. Here we present an original scheme (called multiwasher) to circumvent this problem, and its implementation in an all-refractory thin-film device. Our scheme not only provides good magnetic coupling with a large input coil (0.5 &mgr;H) and very low SQUID inductance, but also shielding from outside uniform fields, such as those generated by ambient disturbances. The measured coupled spectral energy sensitivity in the white region at about 1 kHz is 28ℏ at 4.2 K and 5.5ℏ in a pumped helium bath at 0.9 K. The flux noise spectral density at 0.1 Hz and 0.9 K is&Fgr;n=1×10−6 &Fgr;0/Hz.©1998 American Institute of Physics.
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