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

Applied Physics Letters

Underdamped Josephson junction as a switching current detector

G. Oelsner, L. S. Revin, E. V. Il’ichev, A. L. Pankratov, H.‐G. Meyer, Leif Grönberg, Juha Hassel, L. S. Kuzmin

Published Sep 30, 2013• 58 citations
Publisher

Abstract

We demonstrate the narrow switching distribution of an underdamped Josephson junction from the zero to the finite voltage state at millikelvin temperatures. We argue that such junctions can be used as ultrasensitive detectors of the single photons in the GHz range, operating close to the quantum limit: a given initial (zero voltage) state can be driven by an incoming signal to the finite voltage state. The width of the switching distribution at a nominal temperature of about T = 10 mK was 4.5 nA, which corresponds to an effective noise temperature of the device below 60 mK.

DOI
10.1063/1.4824308

Related papers

Analysis of Josephson Junction Lifetimes for the Detection of Single Photons in a Thermal Noise Background

Alex Stephane Piedjou Komnang, Claudio Guarcello, C. Barone +2 more

This work deals with the numerical analysis of the zero-voltage state lifetimes distribution of an underdamped Josephson junction used for the detection of single microwave photons in the presence of thermal noise. The analysis considers the switching probabilities of a JJ subjected to a train of current pulses, which simulates a weak photon field. To characterize the detection, we take advantage of a statistic tool, the Kumar-Carroll (KC) index, which is a good proxy of the signal-to-noise-ratio. It can be, therefore, exploited to identify the proper device fabrication parameters and the optimal operation point of the junction.

IEEE Workshop on Low Temperature Electronics (WOLTE)•Apr 12, 2021•5 citations

A microwave photon detector

E. V. Il’ichev

The possibility of the implementation of a single-photon detector in the microwave range has been discussed. It has been shown that, for these purposes, it is possible to use an unshunted Josephson junction, which is switched from the superconducting state into a finite-voltage state at the presence of an external signal. The sensitivity of this detector is determined by the distribution of switchings in the absence of an external signal. It has been demonstrated that there is a Josephson junction with a noise temperature below 60 mK at a nominal external temperature of 10 mK. A specific detector intended for the measurement of external microwave signals has been proposed, designed, and fabricated. The first experimental results have been presented.

Physics of the Solid State•Nov 1, 2016•3 citations

Resonant switching current detector based on underdamped Josephson junctions

V. M. Krasnov

Current-biased Josephson junctions can act as detectors of electromagnetic radiation. At optimal conditions, their sensitivity is limited by fluctuations causing stochastic switching from the superconducting to the resistive state. This work provides a quantitative description of a stochastic switching current detector, based on an underdamped Josephson junction. It is shown that activation of a Josephson plasma resonance can greatly enhance the detector responsivity in proportion to the quality factor of the junction. The ways of tuning the detector for achieving optimal operation are discussed. For realistic parameters of Nb / Al O x / Nb tunnel junctions, the sensitivity and noise-equivalent power (NEP) can reach values of S ≃ 5 × 10 12 (V/W) and NEP ≃ 2 × 10 − 23 ( WHz − 1 / 2 ), respectively. These outstanding characteristics facilitate both bolometric and single-photon detection in microwave and terahertz ranges. Published by the American Physical Society 2024

arXiv:2403.03803•Physical Review Applied•Aug 6, 2024•9 citations

Investigation of Current Noise in Underdamped Josephson Devices by Switching Current Measurements

C. Granata, Roberto Russo, Antonio Vettoliere +4 more

Experimental measurements on critical current noise in underdamped niobium based Josephson devices by a technique based on the switching current measurements is reported. By sweeping the junction with a current ramp we measure the critical current switching as a function of the time using the standard time of flight technique. In such a way it is possible to obtain the critical current fluctuations ΔIc=Ic(t)-<Ic(t)> and the relative standard deviations which corresponds to the root square of the current fluctuation power. Pointing at the white noise fluctuations (above few Hz) and taking into account the physical frequency of the device, it is possible to evaluate the power spectral density of the critical current. The analysis has involved high quality underdamped Josephson junctions having an area ranging from (4x4) μm2 to (40x40) μm2 in the temperature range from 4.2 K to few tenth of mK. These measurement provide very useful information about the intrinsic noise of Josephson devices involving SQUIDs and qubits.

Physics Procedia•Jan 1, 2012•2 citations

Experimental demonstrations of Josephson threshold detectors for broadband microwave photons detection

J. X. He, P. H. Ouyang, Y. Q. Chai +3 more

In this Letter, we experimentally demonstrated that Josephson threshold detectors (JTDs) could be developed to implement the sensitive detection of broadband microwave photons. Beginning with the numerical simulations of the damped dynamics for the macroscopic phase particle generated by a Josephson junction (JJ), we showed that the time-domain threshold voltage state switched measurements of the JJ driven by a low-frequency triangular wave current, which could be utilized to implement the sensitive microwave photons detection. The detectable signal power can be determined by using the Kumar–Caroll index to quantify the distinguishability between two statistical distributions on the measured threshold switched durations of the JJ with and without the signal input. Experimentally, we fabricated the Al/AlOx/Al JJ and measured its threshold responses, at 50 mK temperature, to the input microwave photons at the frequency of ∼5 GHz. The experimental results indicated that the weak microwave signals, which are phenomenologically threatened by the additional thermal noise that modifies the damped phase dynamics of the JJ, can be detected by the fabricated JTD. The detectable power of the microwave signals demonstrated here was calibrated as about −92 dBm (corresponding to the photons rate of ∼2×108 photons/ms). Based on the numerical simulations for optimizing the relevant performance indicators of the detectors, we further argue that the JTDs could be utilized to achieve the sensitive detection of broadband microwave photons at the single-photon level.

arXiv:2502.14300•Applied Physics Letters•May 19, 2025•5 citations

Detection of single-mode thermal microwave photons using an underdamped Josephson junction

A. L. Pankratov, Anna V. Gordeeva, Alexander V. Chiginev +4 more

When measuring electromagnetic radiation of frequency f, the most sensitive detector counts single quanta of energy hf. Single photon detectors have been demonstrated from γ-rays to infrared wavelengths, with ongoing efforts to extend their range to microwaves. Here we show that an underdamped Josephson junction can detect 14 GHz thermal photons, with energy 10 yJ or 50 μeV, stochastically emitted by a microwave copper cavity at millikelvin temperatures. After characterizing the source and the detector, we vary the cavity temperature and measure the photon rate. The device achieves 45% efficiency and a dark count rate of 0.1 Hz over several GHz. Demonstrated super-Poissonian photon statistics is a signature of thermal light and a hallmark of quantum chaos. We discuss applications in dark matter axion searches and note its relevance to quantum information and fundamental physics. It is shown that 14 GHz photons, thermally emitted from a copper cavity, can be detected by a Josephson junction with 45% efficiency and 0.1 Hz dark count rate. Demonstrated super-Poissonian photon statistics is a signature of thermal light and a hallmark of quantum chaos.

arXiv:2404.10434•Nature Communications•Apr 11, 2025•21 citations
We demonstrate the narrow switching distribution of an underdamped Josephson junction from the zero to the finite voltage state at millikelvin temperatures. We argue that such junctions can be used as ultrasensitive detectors of the single photons in the GHz range, operating close to the quantum limit: a given initial (zero voltage) state can be driven by an incoming signal to the finite voltage state. The width of the switching distribution at a nominal temperature of about T = 10 mK was 4.5 nA, which corresponds to an effective noise temperature of the device below 60 mK.
This work deals with the numerical analysis of the zero-voltage state lifetimes distribution of an underdamped Josephson junction used for the detection of single microwave photons in the presence of thermal noise. The analysis considers the switching probabilities of a JJ subjected to a train of current pulses, which simulates a weak photon field. To characterize the detection, we take advantage of a statistic tool, the Kumar-Carroll (KC) index, which is a good proxy of the signal-to-noise-ratio. It can be, therefore, exploited to identify the proper device fabrication parameters and the optimal operation point of the junction.
The possibility of the implementation of a single-photon detector in the microwave range has been discussed. It has been shown that, for these purposes, it is possible to use an unshunted Josephson junction, which is switched from the superconducting state into a finite-voltage state at the presence of an external signal. The sensitivity of this detector is determined by the distribution of switchings in the absence of an external signal. It has been demonstrated that there is a Josephson junction with a noise temperature below 60 mK at a nominal external temperature of 10 mK. A specific detector intended for the measurement of external microwave signals has been proposed, designed, and fabricated. The first experimental results have been presented.
Current-biased Josephson junctions can act as detectors of electromagnetic radiation. At optimal conditions, their sensitivity is limited by fluctuations causing stochastic switching from the superconducting to the resistive state. This work provides a quantitative description of a stochastic switching current detector, based on an underdamped Josephson junction. It is shown that activation of a Josephson plasma resonance can greatly enhance the detector responsivity in proportion to the quality factor of the junction. The ways of tuning the detector for achieving optimal operation are discussed. For realistic parameters of Nb / Al O x / Nb tunnel junctions, the sensitivity and noise-equivalent power (NEP) can reach values of S ≃ 5 × 10 12 (V/W) and NEP ≃ 2 × 10 − 23 ( WHz − 1 / 2 ), respectively. These outstanding characteristics facilitate both bolometric and single-photon detection in microwave and terahertz ranges. Published by the American Physical Society 2024
Experimental measurements on critical current noise in underdamped niobium based Josephson devices by a technique based on the switching current measurements is reported. By sweeping the junction with a current ramp we measure the critical current switching as a function of the time using the standard time of flight technique. In such a way it is possible to obtain the critical current fluctuations ΔIc=Ic(t)-<Ic(t)> and the relative standard deviations which corresponds to the root square of the current fluctuation power. Pointing at the white noise fluctuations (above few Hz) and taking into account the physical frequency of the device, it is possible to evaluate the power spectral density of the critical current. The analysis has involved high quality underdamped Josephson junctions having an area ranging from (4x4) μm2 to (40x40) μm2 in the temperature range from 4.2 K to few tenth of mK. These measurement provide very useful information about the intrinsic noise of Josephson devices involving SQUIDs and qubits.
In this Letter, we experimentally demonstrated that Josephson threshold detectors (JTDs) could be developed to implement the sensitive detection of broadband microwave photons. Beginning with the numerical simulations of the damped dynamics for the macroscopic phase particle generated by a Josephson junction (JJ), we showed that the time-domain threshold voltage state switched measurements of the JJ driven by a low-frequency triangular wave current, which could be utilized to implement the sensitive microwave photons detection. The detectable signal power can be determined by using the Kumar–Caroll index to quantify the distinguishability between two statistical distributions on the measured threshold switched durations of the JJ with and without the signal input. Experimentally, we fabricated the Al/AlOx/Al JJ and measured its threshold responses, at 50 mK temperature, to the input microwave photons at the frequency of ∼5 GHz. The experimental results indicated that the weak microwave signals, which are phenomenologically threatened by the additional thermal noise that modifies the damped phase dynamics of the JJ, can be detected by the fabricated JTD. The detectable power of the microwave signals demonstrated here was calibrated as about −92 dBm (corresponding to the photons rate of ∼2×108 photons/ms). Based on the numerical simulations for optimizing the relevant performance indicators of the detectors, we further argue that the JTDs could be utilized to achieve the sensitive detection of broadband microwave photons at the single-photon level.
When measuring electromagnetic radiation of frequency f, the most sensitive detector counts single quanta of energy hf. Single photon detectors have been demonstrated from γ-rays to infrared wavelengths, with ongoing efforts to extend their range to microwaves. Here we show that an underdamped Josephson junction can detect 14 GHz thermal photons, with energy 10 yJ or 50 μeV, stochastically emitted by a microwave copper cavity at millikelvin temperatures. After characterizing the source and the detector, we vary the cavity temperature and measure the photon rate. The device achieves 45% efficiency and a dark count rate of 0.1 Hz over several GHz. Demonstrated super-Poissonian photon statistics is a signature of thermal light and a hallmark of quantum chaos. We discuss applications in dark matter axion searches and note its relevance to quantum information and fundamental physics. It is shown that 14 GHz photons, thermally emitted from a copper cavity, can be detected by a Josephson junction with 45% efficiency and 0.1 Hz dark count rate. Demonstrated super-Poissonian photon statistics is a signature of thermal light and a hallmark of quantum chaos.