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

IEEE Transactions on Applied Superconductivity

SINIS Josephson junctions for programmable Josephson voltage standard circuits

H. Schulze, F. Muller, Ralf Behr, J. Kohlmann, J. Niemeyer, D Balashov

Published Jun 1, 1999• 51 citations
Publisher

Abstract

Nonhysteretic Josephson junctions with a superconductor-insulator-normal metal-insulator-superconductor (SINIS) structure fabricated using the reliable Nb-AlO/sub x/ technology have been used for the design and fabrication of a 1-V inherently stable Josephson voltage standard. The superconducting circuit can be driven at the same microwave frequencies as conventional SIS circuits. The microwave-induced 1-V step is suitable for calibration purposes. The successful operation of the 1-V circuit is due to an internal, phase-locked oscillation of all SINIS junctions which are embedded in a low-impedance strip-line. The microwave power required for exciting the coherent oscillation is very low and allows the integration of low power sources. Even operation without any external microwave source appears to be possible.

DOI
10.1109/77.783961

Related papers

10 V SINIS Josephson junction series arrays for programmable voltage standards

J. Kohlmann, H. Schulze, Ralf Behr +2 more

A programmable dc voltage standard for output voltages of up to 10 V has been realized. The series arrays, consisting of about 69120 overdamped superconductor/insulator/normal metal/insulator/superconductor (SINIS) Josephson junctions, have been fabricated using the reliable Nb-Al/Al/sub 2/O/sub 3/ technology. The arrays can be operated in conventional Josephson voltage standards at microwave frequencies from 70 GHz to 75 GHz. Steps of constant voltage are observed at very low microwave power levels, since the major part of the microwave power is generated by the junctions themselves. The operation of the arrays and the formation of Shapiro steps are discussed.

IEEE Transactions on Instrumentation and Measurement•Apr 1, 2001•20 citations

SNS junction on Nb-Ti base for microwave circuits

M. Schubert, Ludwig Fritzsch, G. Wende +1 more

Superconductor-normal metal-superconductor (SNS) junctions are well-suited for large-scale integrated superconducting circuits. Potential applications are programmable voltage standards, digital-to-analog converters and large-scale RSFQ circuits. The application of SNS junctions provides some advantages, e.g. a simplified fabrication technology and reduced parasitic inductances. But it requires a technological process with dimensions down to the submicrometer region to achieve sufficiently high characteristic voltages I/sub C/R/sub N/. In our process the normal metal interlayer is titanium. Therefore the sidewall insulation of the junctions can be made by anodization, as it is known from the Nb-Al technology. Nb-Ti-Nb Josephson junctions and junction arrays were fabricated down to the submicrometer range with I/sub C/R/sub N/ values up to 87 microvolt depending on the titanium thickness. Their measured critical currents have a small spread of about 10 percent. Shapiro steps are observed under the influence of microwave irradiation. For the application of such junctions in a programmable Josephson voltage standard a new type of microwave circuit using coplanar strips is proposed and successfully tested in 10 V SIS circuits.

IEEE Transactions on Applied Superconductivity•Mar 1, 2001•12 citations

Coplanar strips for Josephson voltage standard circuits

M. Schubert, T. May, G. Wende +2 more

We present a microwave circuit for Josephson voltage standards. Here, the Josephson junctions are integrated in a microwave transmission line designed as coplanar strips (CPS). The new layout offers the possibility of achieving a higher scale of integration and to considerably simplify the fabrication technology. The characteristic impedance of the CPS is about 50 Ω, and this should be of interest for programmable Josephson voltage standard circuits with SNS or SINIS junctions. To demonstrate the function of the microwave circuit design, conventional 10 V Josephson voltage standard circuits with 17 000 Nb/AlOx/Nb junctions were prepared and tested. Stable Shapiro steps at the 10 V level were generated. Furthermore, arrays of 1400 SINIS junctions in this microwave layout exhibited first-order Shapiro steps.

Applied Physics Letters•Aug 13, 2001•22 citations

SNS and SIS Josephson junctions with dimensions down to the submicron region prepared by a unified technology

Ludwig Fritzsch, H. Elsner, M. Schubert +1 more

Several applications of Josephson junctions (JJs) in low-temperature superconducting circuits such as programmable voltage standards and SFQ logical circuits or SQUID sensors require JJs with sub-µm dimensions. A method for preparing superconductor-isolator-superconductor (SIS) JJs as well as superconductor-normal metal-superconductor (SNS) JJs was developed which allows the preparation of both types of junctions by nearly the same technological process. Titanium is used as the normal metal for the SNS JJ. Ti can be anodically oxidized and a technology similar to the well-tried Nb-Al technology for SIS JJs can be applied to the SNS system, too. By electron-beam exposure of a negative deep UV photoresist (ma-N 2400) a stable resist mask is generated which has to withstand the following three self-aligned process steps: etching of the Nb counterelectrode by RIE, isolation by anodization and lifting of a SiO planarization layer. By this process SNS (Nb-Ti-Nb) and SIS (Nb-Al/AlO x -Nb) Josephson junctions with smallest junction areas of 0.49 µm 2 were prepared and characterized by dc measurements and under the influence of microwave irradiation. The Nb-Ti-Nb junctions have I c R n products of 87 µV. They can be used for programmable Josephson voltage standard circuits at frequencies of 70 GHz.

Superconductor Science and Technology•Nov 1, 1999•9 citations

Application of Josephson series arrays to a DC quantum voltmeter

Ralf Behr, L. Grimm, Torsten Funck +6 more

Josephson series arrays with a binary sequence of nonhysteretic superconductor-insulator-normal metal-insulator-superconductor (SINIS) junctions have been realized. The arrays of up to 8192 junctions (14 bits) are operated at microwave frequencies of about 70 GHz with low microwave power. An electronic system was built to drive an automated dc quantum voltmeter. Two electrically isolated quantum voltmeters (QVMs) in the same cryoprobe and driven by one frequency have been used for calibrating resistive dividers with the intention of demonstrating some advantages of these instruments.

IEEE Transactions on Instrumentation and Measurement•Apr 1, 2001•28 citations

Overdamped Josephson junctions for applications to precision measurement

V. Lacquaniti, Domenico Andreone, Matteo Fretto +6 more

Overdamped Nb/Al-AlOx/Nb Josephson junctions are an intermediate state between the SIS and SNS Josephson junctions. With a proper choice of fabrication parameters, stable and reproducible nonhysteretic curent-voltage characteristics have been obtained Featuring critical current densities up to 70 kA/cm2and characteristic voltages up to 450 μV at 4.2 K, overdamped junctions are suitable for many aplications ranging from RSFQ electronic circuits to programmable and ac voltage standards. Tests on single junctions arrays of series-connected junctions have shown a suitable behaviour when driven by a microwave with frequencies around 75 GHz. The quantized steps have proven to be stable and flat at nV level. These junctions also shown an improved temperature dependence, which can be interesting in view of the development instrumentation with an integrated quantum voltage reference operated in a closed cycle refrigerator.

International Workshop on Advances in Sensors and Interfaces (IWASI)•Jan 1, 2007•0 citations
Nonhysteretic Josephson junctions with a superconductor-insulator-normal metal-insulator-superconductor (SINIS) structure fabricated using the reliable Nb-AlO/sub x/ technology have been used for the design and fabrication of a 1-V inherently stable Josephson voltage standard. The superconducting circuit can be driven at the same microwave frequencies as conventional SIS circuits. The microwave-induced 1-V step is suitable for calibration purposes. The successful operation of the 1-V circuit is due to an internal, phase-locked oscillation of all SINIS junctions which are embedded in a low-impedance strip-line. The microwave power required for exciting the coherent oscillation is very low and allows the integration of low power sources. Even operation without any external microwave source appears to be possible.
A programmable dc voltage standard for output voltages of up to 10 V has been realized. The series arrays, consisting of about 69120 overdamped superconductor/insulator/normal metal/insulator/superconductor (SINIS) Josephson junctions, have been fabricated using the reliable Nb-Al/Al/sub 2/O/sub 3/ technology. The arrays can be operated in conventional Josephson voltage standards at microwave frequencies from 70 GHz to 75 GHz. Steps of constant voltage are observed at very low microwave power levels, since the major part of the microwave power is generated by the junctions themselves. The operation of the arrays and the formation of Shapiro steps are discussed.
Superconductor-normal metal-superconductor (SNS) junctions are well-suited for large-scale integrated superconducting circuits. Potential applications are programmable voltage standards, digital-to-analog converters and large-scale RSFQ circuits. The application of SNS junctions provides some advantages, e.g. a simplified fabrication technology and reduced parasitic inductances. But it requires a technological process with dimensions down to the submicrometer region to achieve sufficiently high characteristic voltages I/sub C/R/sub N/. In our process the normal metal interlayer is titanium. Therefore the sidewall insulation of the junctions can be made by anodization, as it is known from the Nb-Al technology. Nb-Ti-Nb Josephson junctions and junction arrays were fabricated down to the submicrometer range with I/sub C/R/sub N/ values up to 87 microvolt depending on the titanium thickness. Their measured critical currents have a small spread of about 10 percent. Shapiro steps are observed under the influence of microwave irradiation. For the application of such junctions in a programmable Josephson voltage standard a new type of microwave circuit using coplanar strips is proposed and successfully tested in 10 V SIS circuits.
We present a microwave circuit for Josephson voltage standards. Here, the Josephson junctions are integrated in a microwave transmission line designed as coplanar strips (CPS). The new layout offers the possibility of achieving a higher scale of integration and to considerably simplify the fabrication technology. The characteristic impedance of the CPS is about 50 Ω, and this should be of interest for programmable Josephson voltage standard circuits with SNS or SINIS junctions. To demonstrate the function of the microwave circuit design, conventional 10 V Josephson voltage standard circuits with 17 000 Nb/AlOx/Nb junctions were prepared and tested. Stable Shapiro steps at the 10 V level were generated. Furthermore, arrays of 1400 SINIS junctions in this microwave layout exhibited first-order Shapiro steps.
Several applications of Josephson junctions (JJs) in low-temperature superconducting circuits such as programmable voltage standards and SFQ logical circuits or SQUID sensors require JJs with sub-µm dimensions. A method for preparing superconductor-isolator-superconductor (SIS) JJs as well as superconductor-normal metal-superconductor (SNS) JJs was developed which allows the preparation of both types of junctions by nearly the same technological process. Titanium is used as the normal metal for the SNS JJ. Ti can be anodically oxidized and a technology similar to the well-tried Nb-Al technology for SIS JJs can be applied to the SNS system, too. By electron-beam exposure of a negative deep UV photoresist (ma-N 2400) a stable resist mask is generated which has to withstand the following three self-aligned process steps: etching of the Nb counterelectrode by RIE, isolation by anodization and lifting of a SiO planarization layer. By this process SNS (Nb-Ti-Nb) and SIS (Nb-Al/AlO x -Nb) Josephson junctions with smallest junction areas of 0.49 µm 2 were prepared and characterized by dc measurements and under the influence of microwave irradiation. The Nb-Ti-Nb junctions have I c R n products of 87 µV. They can be used for programmable Josephson voltage standard circuits at frequencies of 70 GHz.
Josephson series arrays with a binary sequence of nonhysteretic superconductor-insulator-normal metal-insulator-superconductor (SINIS) junctions have been realized. The arrays of up to 8192 junctions (14 bits) are operated at microwave frequencies of about 70 GHz with low microwave power. An electronic system was built to drive an automated dc quantum voltmeter. Two electrically isolated quantum voltmeters (QVMs) in the same cryoprobe and driven by one frequency have been used for calibrating resistive dividers with the intention of demonstrating some advantages of these instruments.
Overdamped Nb/Al-AlOx/Nb Josephson junctions are an intermediate state between the SIS and SNS Josephson junctions. With a proper choice of fabrication parameters, stable and reproducible nonhysteretic curent-voltage characteristics have been obtained Featuring critical current densities up to 70 kA/cm2and characteristic voltages up to 450 μV at 4.2 K, overdamped junctions are suitable for many aplications ranging from RSFQ electronic circuits to programmable and ac voltage standards. Tests on single junctions arrays of series-connected junctions have shown a suitable behaviour when driven by a microwave with frequencies around 75 GHz. The quantized steps have proven to be stable and flat at nV level. These junctions also shown an improved temperature dependence, which can be interesting in view of the development instrumentation with an integrated quantum voltage reference operated in a closed cycle refrigerator.