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

Japanese Journal of Applied Physics

Experiments on a Point-Contact Josephson Mixer at 469 µm

Masayoshi Kobayashi, Shinji Ohara, Akira Katsuno, Kiyomi Sakai, Hideo Ogawa

Published Nov 1, 1985• 1 citation
Publisher

Abstract

An Nb point-contact Josephson mixer with a corner reflector behind the Nb 4-wavelength wire antenna was constructed, and experiments were carried out at 469 µm (693 GHz). A 10 dB improvement in coupling efficiency was obtained by using the reflector. An SSB (single-side-band) mixer noise temperature of 1660 K was obtained, and the conversion efficiency of the mixer was -35.7 dB in the 9th harmonic mixing between 71 GHz LO and 693 GHz signal.

DOI
10.1143/jjap.24.1459

Related papers

Progress on millimeter wave Josephson junction mixers

Y. Taur, Anthony R. Kerr

Preset, recyclable Nb point contacts are tested as low‐noise Josephson mixers at a signal frequency of 115 GHz. The best result achieved is a mixer noise temperature (single sideband) of 120 K with unity conversion efficiency (SSB) for a junction at 6 K. Variation of mixer properties with temperature and other parameters is presented.

AIP conference proceedings•Jan 1, 1978•1 citation

Low-noise Josephson mixers at 115 GHz using recyclable point contacts

Y. Taur, Anthony R. Kerr

Thermally recyclable Nb point-contact Josephson junctions are investigated as low-noise mixers with an external local oscillator at 115 GHz. The best single sideband mixer noise temperature achieved is 140 (±20) K with a (SSB) conversion loss of 2.4 (±0.5) dB. Such rugged junctions are suitable for use in practical receivers and should give unprecedented sensitivity at the shorter millimeter wavelengths.

Applied Physics Letters•Jun 1, 1978•32 citations

Josephson heterodyne detection at high thermal background levels

Tim Poorter

Point-contact Josephson junctions with a submicron contact diameter have been used as high-frequency mixers (170–220 GHz) under high thermal background conditions. The junction is formed across a full height (0.56×1.06 mm2) waveguide between a 3–5-μm thick Nb whisker and a 0.2-mm diam Nb center conductor of a coaxial line. The best single-side band mixer-noise temperature that was measured is 165 K (± 25%) with a corresponding single-side band conversion efficiency of 0.36±0.03 (a loss of 4.5 ±0.4 dB) at a signal frequency of 185 GHz, including losses in the coupling horn and the waveguide. The performance was measured with the hot-cold source technique. The effects of nonheterodyne response in that situation were investigated in detail. The junctions have been operated in a coherent receiver that can be used on a telescope with only small adaptations. The instantaneous bandwidth of the receiver is about 20 GHz.

Journal of Applied Physics•Jan 1, 1982•27 citations

Frequency conversion with superconducting point contacts operating as oscillator-mixers and its application to the measurement of the linewidth of the Josephson current at very high frequency

G. Vernet, Robert Adde

The Josephson frequency conversion in the millimeter and submillimeter wave region is studied with superconducting Nb-Nb point contact junctions at 4.2 K, using the contact both as the local oscillator and the mixer with intermediate frequencies of 0.1 and 9.2 GHz. Frequency conversion signals are only detected in the latter case with a microwave receiver at 9.2 GHz in a range of Josephson frequencies between 145 and 1 600 GHz. The experiments with intermediate frequency fi of 0.1 GHz indicate for this small value of f i that the observed signals are not related to frequency conversion but noise effects. An analysis of the frequency conversion mechanism in a Josephson junction operated as an oscillator-mixer is proposed which includes the noise effects and also the feedback effects induced in a junction driven by a constant current source. We have then investigated the noise properties up to 450 GHz of superconducting point-contacts using the junction as an oscillator-mixer where the Josephson current is mixed with harmonics of an externally applied signal. The emitted intermediate frequency is detected at 9.2 GHz and its linewidth is measured. In the very high frequency range the dc quasiparticle current dominates in a Josephson weak-link and we compare the corresponding theoretical linewidth calculated by Scalapino with our experimental results.

Revue de Physique Appliquée•Jan 1, 1974•3 citations

Heterodyne reception at 891 GHz using a Josephson harmonic mixer and a microwave local oscillator

T. G. Blaney, D. J. E. Knight

The performance of Nb-Nb point-contact Josephson junction mixers was investigated experimentally with signals from a 891 GHz laser. The local oscillator (LO) was provided by the appropriate junction-generated harmonic of either a 74 or 99 GHz klystron. The intermediate frequency (IF) power varied linearly with signal power for signals less than 10 −5 to 10 −6 W. The optimum conversion loss (from 891 GHz to the IF) was not significantly different for the two klystron frequencies used: the lowest useful conversion loss for the whole mixing system including the signal input matching loss, was 42 (±3) dB. This is 10 dB greater than that observed with a 891 GHz laser LO and the same junction apparatus. Conversion loss of the mixer element alone was independent of IF with the latter varied up to 1·2 GHz. The noise at the output of the IF system was usually dominated by that of the transistor preamplifier with a noise temperature of about 500 K. Thus the input signal necessary to give a signal-to-noise ratio of one at the IF was equivalent to 10 −16 W Hz −1 of IF bandwidth. This mixing system, which can be significantly improved, forms the basis of a fully tunable heterodyne receiver for the submillimetre region.

Journal of Physics D Applied Physics•Sep 21, 1974•11 citations

Josephson frequency conversion in the range 145–1600 GHz with Nb–Nb superconducting point contacts used as oscillator-mixer

G. Vernet, Robert Adde

The Josephson frequency conversion in the millimeter and submillimeter wave region is studied with superconducting Nb–Nb point-contact junctions at 4.2 °K, using the contact both as the local oscillator and the mixer with intermediate frequencies of 0.1, 0.3, and 9.2 GHz. The point contact is in a nonresonant structure and fed by a constant current source: neither a strong rf coupling of the contact with a cavity nor a stabilizing shunt resistance was proved necessary. The direct observation of frequency conversion was performed with a microwave receiver at 9.2 GHz in a range of Josephson frequencies between 145 and 1600 GHz. The experiments with intermediate frequencies fi of 0.1 and 0.3 GHz indicate that conventional frequency conversion does not occur but that the observed signals are related to noise effects. An analysis of the frequency conversion mechanism in a Josephson junction operated as an oscillator-mixer is proposed which includes the noise effects and also the feedback effects induced in a junction driven by a constant current source. The results show that low-frequency current components are induced in the junction, which can give large spurious signals when small i.f. are used.

Journal of Applied Physics•Jun 1, 1974•13 citations
An Nb point-contact Josephson mixer with a corner reflector behind the Nb 4-wavelength wire antenna was constructed, and experiments were carried out at 469 µm (693 GHz). A 10 dB improvement in coupling efficiency was obtained by using the reflector. An SSB (single-side-band) mixer noise temperature of 1660 K was obtained, and the conversion efficiency of the mixer was -35.7 dB in the 9th harmonic mixing between 71 GHz LO and 693 GHz signal.
Point-contact Josephson junctions with a submicron contact diameter have been used as high-frequency mixers (170–220 GHz) under high thermal background conditions. The junction is formed across a full height (0.56×1.06 mm2) waveguide between a 3–5-μm thick Nb whisker and a 0.2-mm diam Nb center conductor of a coaxial line. The best single-side band mixer-noise temperature that was measured is 165 K (± 25%) with a corresponding single-side band conversion efficiency of 0.36±0.03 (a loss of 4.5 ±0.4 dB) at a signal frequency of 185 GHz, including losses in the coupling horn and the waveguide. The performance was measured with the hot-cold source technique. The effects of nonheterodyne response in that situation were investigated in detail. The junctions have been operated in a coherent receiver that can be used on a telescope with only small adaptations. The instantaneous bandwidth of the receiver is about 20 GHz.
The Josephson frequency conversion in the millimeter and submillimeter wave region is studied with superconducting Nb-Nb point contact junctions at 4.2 K, using the contact both as the local oscillator and the mixer with intermediate frequencies of 0.1 and 9.2 GHz. Frequency conversion signals are only detected in the latter case with a microwave receiver at 9.2 GHz in a range of Josephson frequencies between 145 and 1 600 GHz. The experiments with intermediate frequency fi of 0.1 GHz indicate for this small value of f i that the observed signals are not related to frequency conversion but noise effects. An analysis of the frequency conversion mechanism in a Josephson junction operated as an oscillator-mixer is proposed which includes the noise effects and also the feedback effects induced in a junction driven by a constant current source. We have then investigated the noise properties up to 450 GHz of superconducting point-contacts using the junction as an oscillator-mixer where the Josephson current is mixed with harmonics of an externally applied signal. The emitted intermediate frequency is detected at 9.2 GHz and its linewidth is measured. In the very high frequency range the dc quasiparticle current dominates in a Josephson weak-link and we compare the corresponding theoretical linewidth calculated by Scalapino with our experimental results.
The performance of Nb-Nb point-contact Josephson junction mixers was investigated experimentally with signals from a 891 GHz laser. The local oscillator (LO) was provided by the appropriate junction-generated harmonic of either a 74 or 99 GHz klystron. The intermediate frequency (IF) power varied linearly with signal power for signals less than 10 −5 to 10 −6 W. The optimum conversion loss (from 891 GHz to the IF) was not significantly different for the two klystron frequencies used: the lowest useful conversion loss for the whole mixing system including the signal input matching loss, was 42 (±3) dB. This is 10 dB greater than that observed with a 891 GHz laser LO and the same junction apparatus. Conversion loss of the mixer element alone was independent of IF with the latter varied up to 1·2 GHz. The noise at the output of the IF system was usually dominated by that of the transistor preamplifier with a noise temperature of about 500 K. Thus the input signal necessary to give a signal-to-noise ratio of one at the IF was equivalent to 10 −16 W Hz −1 of IF bandwidth. This mixing system, which can be significantly improved, forms the basis of a fully tunable heterodyne receiver for the submillimetre region.
The Josephson frequency conversion in the millimeter and submillimeter wave region is studied with superconducting Nb–Nb point-contact junctions at 4.2 °K, using the contact both as the local oscillator and the mixer with intermediate frequencies of 0.1, 0.3, and 9.2 GHz. The point contact is in a nonresonant structure and fed by a constant current source: neither a strong rf coupling of the contact with a cavity nor a stabilizing shunt resistance was proved necessary. The direct observation of frequency conversion was performed with a microwave receiver at 9.2 GHz in a range of Josephson frequencies between 145 and 1600 GHz. The experiments with intermediate frequencies fi of 0.1 and 0.3 GHz indicate that conventional frequency conversion does not occur but that the observed signals are related to noise effects. An analysis of the frequency conversion mechanism in a Josephson junction operated as an oscillator-mixer is proposed which includes the noise effects and also the feedback effects induced in a junction driven by a constant current source. The results show that low-frequency current components are induced in the junction, which can give large spurious signals when small i.f. are used.