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

Physical review. B, Condensed matter

Closely coupled superconducting microbridges

H. Smith, M. Dion

Published Jul 1, 1990• 6 citations
Publisher

Abstract

Two closely coupled superconducting microbridges have been fabricated with the length of the separating superconducting region less than a coherence length. These microbridges exhibit coupling even when there is zero bias potential at each microbridge. The critical current of each microbridge is a function of the bias current of the other microbridge. This type of coupling is explained by a coupling current that is proportional to the sine of the sum of the phases of both microbridges.

DOI
10.1103/physrevb.42.206

Related papers

OF JOSEPHSON MICROBRIDGES COUPLED BY SUPERCONDUCTING LOOPS

C. Varmazis

We have studied the phase locking of two and eight microbridge arrays shunted by superconducting loops in a dc SQUID configuration. The difference in phase between adjacent bridges is controlled by the applied flux, and thus the radiated power is a periodic function of this flux. With adjustment of the external flux, the individual bridge voltages can be made to add in phase. The effect of additional normal shunts on the phase locking is also investigated. MICROBRIDGES COUPLED BY SUPERCONDUCTING LOOPS Experiment sly on two Josephson microbridges have shown that it is possible to obtain nearly complete in phase coherent radiation with narrowed linewidth by coupling the microbridges with external shunts. To obtain greater ouput power and narrower linewidth it is desirable to phase lock larger arrays of bridges. The narrow range of bias currents over which locking occurs, however, imposes strict tolerances on the uniformity of bridge characteristics if a single current bias is used. In this paper we discuss experiments which eliminate this difficulty by using a superconducting loop to couple the junctions, i.e., a dc SQUID configuration, so that the average frequency of each junction is always equal even for non-identical junctions. Also the phase difference between the junctions in the absence Of noise is set by the amount of externally applied flux due to the fluxoid quantization condition. With identical bridges and zero applied flux, the junctions oscillate in phase. In the geometry used in

•Jan 1, 1979•0 citations

Direct detection of the Josephson current in Nb superconducting microbridges

Paul Crozat, G. Vernet, Robert Adde

The detection of the ac Josephson current in Nb microbridges with dimensions larger than the coherence length but smaller than the effective penetration depth is reported at frequencies between 1.7 and 180 GHz. Precise Josephson linewidth measurements are performed as a function of dc bias and frequency and the results are compared with the existing theories.

Applied Physics Letters•Apr 15, 1978•4 citations

Superconducting Microbridge Junctions Fabricated using Focused Ion Beams

Giuseppe Carlo Tettamanzi, Chris I. Pakes, Alessandro Potenza +3 more

Sub-micron superconducting electronic devices may play a role in the realisation of proposed architectures for quantum computing and metrology. Further miniaturisation of superconducting electronics relies on the ability to fabricate the basic building block, the Josephson junction, on the scale of the superconducting coherence length, with sufficient accuracy that the junction characteristics may be controlled. Making use of focused ion beam technology to fabricate thin-film Nb microbridge devices, we examine the evolution of device characteristics with dimension, focusing on control of the critical current and suppression of superconductivity due to phase-slip behaviour.

•Jan 1, 2006•4 citations

Voltage locking in two coupled microbridge Josephson junctions

D. W. Jillie, James E. Lukens, Y. H. Kao

Voltage locking, defined as the production of an identical non-zero DC voltage in the absence of external microwave radiation across each Josephson junction of an array, has been observed in two microbridge Josephson junctions separated by a 2μm wide strip of superconductor. Voltage locking occurs when the bridges are biased with the current flowing in opposing directions thru the bridges and out the strip connecting them. The voltage across each bridge can be pulled over 1μV until each bridge displays an identical non-zero voltage, with the total voltage across both bridges equal to zero. Full locking, as defined above, is observed in excess of 40μV. The voltage and temperature dependence of the locking is described.

IEEE Transactions on Magnetics•Jan 1, 1977•16 citations

Coherent arrays of thin-film Josephson microbridges

Jørn Bindslev Hansen, P. E. Lindelöf, Thomas F. Finnegan

We have investigated two different methods of coupling between the Josephson oscillations in arrays of superconducting microbridges made of Sn and In in order to establish a single free-running coherent state. We report on experiments involving a broadband inductive coupling between pairs of microbridges, each pair constituting a dc-SQUID; and a narrow hand coupling between microbridges via resonant structures in transmission lines consisting of microstrip or slot lines. We discuss the properties of these two ways of long range coupling of Josephson weak links and evaluate their potential for high-frequency applications.

IEEE Transactions on Magnetics•Jan 1, 1981•17 citations

Controllable Superconducting Nb Long Microbridge by Low Frequency, and Its Resonant Characteristics

Keiji Tsukada, T. Morooka

A Nb superconducting microbridge is fabricated, 40-µm long, less than 0.25-µm wide and 0.1-µm thick. Four-terminal measurement of the I-V characteristics reveals hysterisis in the I-V curve. The microbridge has an excess current over its current in its normal state. Frequency resonance appears over the range of a few hundred kiloherz by electromagnetic wave radiation. The I-V characteristics show that critical current I c is depressed, and as radiation power increases I c decreases. This phenomenon is thought to be due to resonance of quasiparticles in the microbridge, and to resonance restricting the supercurrent.

Japanese Journal of Applied Physics•Nov 1, 1992•0 citations
Two closely coupled superconducting microbridges have been fabricated with the length of the separating superconducting region less than a coherence length. These microbridges exhibit coupling even when there is zero bias potential at each microbridge. The critical current of each microbridge is a function of the bias current of the other microbridge. This type of coupling is explained by a coupling current that is proportional to the sine of the sum of the phases of both microbridges.
We have studied the phase locking of two and eight microbridge arrays shunted by superconducting loops in a dc SQUID configuration. The difference in phase between adjacent bridges is controlled by the applied flux, and thus the radiated power is a periodic function of this flux. With adjustment of the external flux, the individual bridge voltages can be made to add in phase. The effect of additional normal shunts on the phase locking is also investigated. MICROBRIDGES COUPLED BY SUPERCONDUCTING LOOPS Experiment sly on two Josephson microbridges have shown that it is possible to obtain nearly complete in phase coherent radiation with narrowed linewidth by coupling the microbridges with external shunts. To obtain greater ouput power and narrower linewidth it is desirable to phase lock larger arrays of bridges. The narrow range of bias currents over which locking occurs, however, imposes strict tolerances on the uniformity of bridge characteristics if a single current bias is used. In this paper we discuss experiments which eliminate this difficulty by using a superconducting loop to couple the junctions, i.e., a dc SQUID configuration, so that the average frequency of each junction is always equal even for non-identical junctions. Also the phase difference between the junctions in the absence Of noise is set by the amount of externally applied flux due to the fluxoid quantization condition. With identical bridges and zero applied flux, the junctions oscillate in phase. In the geometry used in
Sub-micron superconducting electronic devices may play a role in the realisation of proposed architectures for quantum computing and metrology. Further miniaturisation of superconducting electronics relies on the ability to fabricate the basic building block, the Josephson junction, on the scale of the superconducting coherence length, with sufficient accuracy that the junction characteristics may be controlled. Making use of focused ion beam technology to fabricate thin-film Nb microbridge devices, we examine the evolution of device characteristics with dimension, focusing on control of the critical current and suppression of superconductivity due to phase-slip behaviour.
Voltage locking, defined as the production of an identical non-zero DC voltage in the absence of external microwave radiation across each Josephson junction of an array, has been observed in two microbridge Josephson junctions separated by a 2μm wide strip of superconductor. Voltage locking occurs when the bridges are biased with the current flowing in opposing directions thru the bridges and out the strip connecting them. The voltage across each bridge can be pulled over 1μV until each bridge displays an identical non-zero voltage, with the total voltage across both bridges equal to zero. Full locking, as defined above, is observed in excess of 40μV. The voltage and temperature dependence of the locking is described.
We have investigated two different methods of coupling between the Josephson oscillations in arrays of superconducting microbridges made of Sn and In in order to establish a single free-running coherent state. We report on experiments involving a broadband inductive coupling between pairs of microbridges, each pair constituting a dc-SQUID; and a narrow hand coupling between microbridges via resonant structures in transmission lines consisting of microstrip or slot lines. We discuss the properties of these two ways of long range coupling of Josephson weak links and evaluate their potential for high-frequency applications.
A Nb superconducting microbridge is fabricated, 40-µm long, less than 0.25-µm wide and 0.1-µm thick. Four-terminal measurement of the I-V characteristics reveals hysterisis in the I-V curve. The microbridge has an excess current over its current in its normal state. Frequency resonance appears over the range of a few hundred kiloherz by electromagnetic wave radiation. The I-V characteristics show that critical current I c is depressed, and as radiation power increases I c decreases. This phenomenon is thought to be due to resonance of quasiparticles in the microbridge, and to resonance restricting the supercurrent.