Noise analysis of the double-loop SQUID with unshunted junctions

Mikko Kiviranta; Heikki Seppä

doi:10.1109/77.783639

Noise analysis of the double-loop SQUID with unshunted junctions

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Abstract

The unshunted (un) SQUID is a two-junction device whose Josephson junctions are damped at high frequencies only. Single-valued rather than hysteretic behaviour on the negative resistance region is obtained by using a voltage bias rather than a current bias. We have studied numerically the noise properties of the un SQUID with a double-loop (dl) washer configuration, in which the SQUID inductance is capacitively split into two loops. Our simulations with /spl beta//sub c/=0.7 and /spl beta//sub l/=0.5-3 suggest that noise level in the un dl SQUID depends more weakly on the device parameters than in the un SQUID. The best energy resolution obtained in the smooth area of the IV curves is /spl epsiv//spl ap/5k/sub B/T/spl radic/(LC) but in narrow pockets in the non-smooth region /spl epsiv//spl ap/3k/sub B/T/spl radic/(LC) is approached.

Original language	English
Pages (from-to)	2911-2914
Number of pages	4
Journal	IEEE Transactions on Applied Superconductivity
Volume	9
Issue number	2
DOIs	https://doi.org/10.1109/77.783639
Publication status	Published - 1999
MoE publication type	A1 Journal article-refereed

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Kiviranta, M., & Seppä, H. (1999). Noise analysis of the double-loop SQUID with unshunted junctions. IEEE Transactions on Applied Superconductivity, 9(2), 2911-2914. https://doi.org/10.1109/77.783639

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title = "Noise analysis of the double-loop SQUID with unshunted junctions",

abstract = "The unshunted (un) SQUID is a two-junction device whose Josephson junctions are damped at high frequencies only. Single-valued rather than hysteretic behaviour on the negative resistance region is obtained by using a voltage bias rather than a current bias. We have studied numerically the noise properties of the un SQUID with a double-loop (dl) washer configuration, in which the SQUID inductance is capacitively split into two loops. Our simulations with /spl beta//sub c/=0.7 and /spl beta//sub l/=0.5-3 suggest that noise level in the un dl SQUID depends more weakly on the device parameters than in the un SQUID. The best energy resolution obtained in the smooth area of the IV curves is /spl epsiv//spl ap/5k/sub B/T/spl radic/(LC) but in narrow pockets in the non-smooth region /spl epsiv//spl ap/3k/sub B/T/spl radic/(LC) is approached.",

author = "Mikko Kiviranta and Heikki Sepp{\"a}",

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year = "1999",

doi = "10.1109/77.783639",

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AU - Kiviranta, Mikko

AU - Seppä, Heikki

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N2 - The unshunted (un) SQUID is a two-junction device whose Josephson junctions are damped at high frequencies only. Single-valued rather than hysteretic behaviour on the negative resistance region is obtained by using a voltage bias rather than a current bias. We have studied numerically the noise properties of the un SQUID with a double-loop (dl) washer configuration, in which the SQUID inductance is capacitively split into two loops. Our simulations with /spl beta//sub c/=0.7 and /spl beta//sub l/=0.5-3 suggest that noise level in the un dl SQUID depends more weakly on the device parameters than in the un SQUID. The best energy resolution obtained in the smooth area of the IV curves is /spl epsiv//spl ap/5k/sub B/T/spl radic/(LC) but in narrow pockets in the non-smooth region /spl epsiv//spl ap/3k/sub B/T/spl radic/(LC) is approached.

AB - The unshunted (un) SQUID is a two-junction device whose Josephson junctions are damped at high frequencies only. Single-valued rather than hysteretic behaviour on the negative resistance region is obtained by using a voltage bias rather than a current bias. We have studied numerically the noise properties of the un SQUID with a double-loop (dl) washer configuration, in which the SQUID inductance is capacitively split into two loops. Our simulations with /spl beta//sub c/=0.7 and /spl beta//sub l/=0.5-3 suggest that noise level in the un dl SQUID depends more weakly on the device parameters than in the un SQUID. The best energy resolution obtained in the smooth area of the IV curves is /spl epsiv//spl ap/5k/sub B/T/spl radic/(LC) but in narrow pockets in the non-smooth region /spl epsiv//spl ap/3k/sub B/T/spl radic/(LC) is approached.

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