Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

physica status solidi (a)

On the storage and detection of multiple flux quantum states in this film double SQUIDs

Wolfgang Schmidt, Stefan H. Heinemann

Published Nov 16, 1983• 0 citations
Publisher

Abstract

The conditions for storing and detecting multiple flux quantum states by means of the so-called double SQUID are estimated by a linear approximation. The double SQUID consists of two 2-Junction SQUIDs coupled via a joint inductance. First experimental results show that by means of the double SQUID the maximum number of 13 flux quanta can be stored and also detected exactly.

DOI
10.1002/pssa.2210800115

Related papers

On the Storage and Detection of Multiple Flux Quantum States in Thin Film Double SQUIDs

Wolfgang Schmidt, Stefan H. Heinemann

De Gruyter eBooks•Dec 31, 1983•0 citations

Analysis on the Suitability of Bi-SQUIDs for the Detection of Trapped Flux in Superconducting Circuits

Tessa Hall, Coenrad Johann Fourie

Quantised magnetic flux trapped during cooldown in superconducting integrated circuits, particularly in thin-film ground planes, couples to nearby circuit structures. The coupling from such fluxons is known to degrade circuit operating margins, or to cause outright operational failure. Measurement of the likely location of one or more trapped fluxons during circuit operation, as well as before and after defluxing steps, can help improve defluxing methods and increase circuit operating margins. A bi-SQUID is a device consisting of three Josephson junctions which demonstrates improved linearity in the voltage-flux response over conventional DC SQUIDs. Conventional DC SQUIDs are being considered as a means of implementing trapped flux detection. Due to the improved linearity of bi-SQUIDs, we investigate their suitability for the same purpose. We present simulation results comparing the sensitivity of different bi-SQUID designs and layout structures to trapped flux and compare bi-SQUID results with a conventional DC SQUID.

IEEE Transactions on Applied Superconductivity•Nov 24, 2025•0 citations

Store–restore operation of flux quanta in coplanar type high Tc superconductive quantum interference devices

Hiroyuki Fuke, Kazuo Saitoh, Tadashi Utagawa +1 more

For a superconductive quantum interference device (SQUID) with rather large loop inductance for a single flux quantum, store–restore operation of flux quanta has been examined by external current pulses. To sense the stored flux quanta, the device includes another directly coupled SQUID as a magnetometer. Both of the coplanar type dc SQUIDs have been composed of Josephson junctions made by the narrow-focused ion beam irradiation technique in single-layer NdBa2Cu3O7−δ superconducting films. The SQUID has a critical current of 375 μA and an inductive parameter (βL) of 32. The number of stored flux quanta is controlled by the pulse signal height and the input terminal, but not by the number of pulses.

Journal of Applied Physics•Sep 1, 1998•2 citations

Theory of signal and noise performance of superconducting quantum interferometers with two quantization loops

Ya. S. Greenberg, G.S. Krivoy, H. Koch

The superconducting quantum interferometer with two quantization loops, the so-called double SQUID, or D-SQUID, is a modification of the well-known rf SQUID. The modification consists of a replacement of the one junction of the rf SQUID by a superconducting loop with two Josephson junctions. This device can be used to transform the weak magnetic flux applied to the loop with junctions to a voltage across the tank circuit inductively coupled to the other loop. As has previously been shown in experiments [G. S. Krivoy and H. Koch, J. Appl. Phys. 74, 2925 (1993)], D-SQUIDs have an extremely large output signal swing up to 1 mV and a transfer function of several mV/(h/2e). In this paper, a D-SQUID theory using a numerical and an analytical approach is developed. The theoretical results are compared with the above-mentioned experiments.

Journal of Applied Physics•May 1, 1995•4 citations

Quantum transitions in the double-hole SQUID

J. Vrba, Alistair A. Fife, V. Macura +2 more

A generalized theory of the double-hole SQUID is developed and the importance of the mutual inductive coupling between the SQUID holes is demonstrated. The basic flux periodicity Φeff is found to depend on this inductive coupling and is shown to be within the limits Φ0 ≤ Φeff ≤ 2Φ0 for coupling constant k in the range 1 ≥ k ≥ 0.

Canadian Journal of Physics•Oct 1, 1976•2 citations

An integrated system of SQUIDs for the study of macroscopic quantum coherence

C. Cosmelli, Maria Gabriella Castellano, Roberto Leoni +3 more

The observation and study of macroscopic quantum coherence (MQC), i.e. the coherent superposition and evolution of macroscopically distinct quantum states, is of great importance for both our understanding of nature and for quantum engineering, for example in quantum computing. Recently a first indication of MQC in a system of SQUIDs has been indirectly observed by means of spectroscopic techniques. Applications like quantum computing, however, require the manipulation and the observation of the time evolution of the MQC states. We have realized a system of SQUIDs for the study of MQC. Our system, based on trilayer Nb/AlOx/Nb technology, consists of a double rf-SQUID, source of the MQC state, inductively coupled to a non-hysteretic dc-SQUID magnetometer and to a hysteretic dc-SQUID threshold detector, used for the read-out of the magnetic flux state. The magnetometer is used to test and monitor the rf-SQUID behaviour, while the hysteretic dc-SQUID is used to perform fast measurements with a reduced back action on the rf-SQUID. We present measurements performed at 4.2 K and at 20 mK to characterize the single devices and their overall behaviour, and a scheme for the use of a set of SQUIDs as a qubit system.

Superconductor Science and Technology•Nov 21, 2001•7 citations
The conditions for storing and detecting multiple flux quantum states by means of the so-called double SQUID are estimated by a linear approximation. The double SQUID consists of two 2-Junction SQUIDs coupled via a joint inductance. First experimental results show that by means of the double SQUID the maximum number of 13 flux quanta can be stored and also detected exactly.
Quantised magnetic flux trapped during cooldown in superconducting integrated circuits, particularly in thin-film ground planes, couples to nearby circuit structures. The coupling from such fluxons is known to degrade circuit operating margins, or to cause outright operational failure. Measurement of the likely location of one or more trapped fluxons during circuit operation, as well as before and after defluxing steps, can help improve defluxing methods and increase circuit operating margins. A bi-SQUID is a device consisting of three Josephson junctions which demonstrates improved linearity in the voltage-flux response over conventional DC SQUIDs. Conventional DC SQUIDs are being considered as a means of implementing trapped flux detection. Due to the improved linearity of bi-SQUIDs, we investigate their suitability for the same purpose. We present simulation results comparing the sensitivity of different bi-SQUID designs and layout structures to trapped flux and compare bi-SQUID results with a conventional DC SQUID.
For a superconductive quantum interference device (SQUID) with rather large loop inductance for a single flux quantum, store–restore operation of flux quanta has been examined by external current pulses. To sense the stored flux quanta, the device includes another directly coupled SQUID as a magnetometer. Both of the coplanar type dc SQUIDs have been composed of Josephson junctions made by the narrow-focused ion beam irradiation technique in single-layer NdBa2Cu3O7−δ superconducting films. The SQUID has a critical current of 375 μA and an inductive parameter (βL) of 32. The number of stored flux quanta is controlled by the pulse signal height and the input terminal, but not by the number of pulses.
The superconducting quantum interferometer with two quantization loops, the so-called double SQUID, or D-SQUID, is a modification of the well-known rf SQUID. The modification consists of a replacement of the one junction of the rf SQUID by a superconducting loop with two Josephson junctions. This device can be used to transform the weak magnetic flux applied to the loop with junctions to a voltage across the tank circuit inductively coupled to the other loop. As has previously been shown in experiments [G. S. Krivoy and H. Koch, J. Appl. Phys. 74, 2925 (1993)], D-SQUIDs have an extremely large output signal swing up to 1 mV and a transfer function of several mV/(h/2e). In this paper, a D-SQUID theory using a numerical and an analytical approach is developed. The theoretical results are compared with the above-mentioned experiments.
The observation and study of macroscopic quantum coherence (MQC), i.e. the coherent superposition and evolution of macroscopically distinct quantum states, is of great importance for both our understanding of nature and for quantum engineering, for example in quantum computing. Recently a first indication of MQC in a system of SQUIDs has been indirectly observed by means of spectroscopic techniques. Applications like quantum computing, however, require the manipulation and the observation of the time evolution of the MQC states. We have realized a system of SQUIDs for the study of MQC. Our system, based on trilayer Nb/AlOx/Nb technology, consists of a double rf-SQUID, source of the MQC state, inductively coupled to a non-hysteretic dc-SQUID magnetometer and to a hysteretic dc-SQUID threshold detector, used for the read-out of the magnetic flux state. The magnetometer is used to test and monitor the rf-SQUID behaviour, while the hysteretic dc-SQUID is used to perform fast measurements with a reduced back action on the rf-SQUID. We present measurements performed at 4.2 K and at 20 mK to characterize the single devices and their overall behaviour, and a scheme for the use of a set of SQUIDs as a qubit system.