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

Shapiro steps observed in a dc superconducting quantum interference device with multiple junctions in each arm

L. Chen, P. Chen, C. K. Ong

Published Feb 11, 2002• 6 citations
Publisher

Abstract

A high-Tc dc superconducting quantum interference device (SQUID) with three Josephson junctions (JJs) in series in each of its arms has been fabricated. Its Shapiro steps were studied using microwave (rf) radiation of 10 GHz and weak magnetic fields. The appearance of giant Shapiro steps and of some of half-integer steps was observed. Separation between the adjacent Shapiro steps could be tuned by rf magnetic fields and small external dc magnetic fields. This phenomenon was analyzed by phase locking the JJs in the SQUID.

DOI
10.1063/1.1447598

Related papers

Shapiro steps in a dc quantum interference device with multiple identical junctions in each arm

Roberto De Luca, Francesco Romeo

Integer and half-integer Shapiro step amplitudes in the current-voltage characteristics of symmetric superconducting quantum interference devices (SQUIDS), containing more than one Josephson junction on each arm, are analytically calculated for small values of the parameter β and in the absence of noise. This analysis is made possible by the reduction of the dynamical equations of the multiple-junction SQUID to the dynamical equation of a single Josephson junction possessing a nonconventional current-phase relation.

Journal of Applied Physics•Oct 1, 2005•5 citations

Half-integer Shapiro-steps in superconducting qubit with a π-Josephson junction

Michiyasu Mori, Sadamichi Maekawa

Abstract A superconducting quantum interference device (SQUID) comprising 0- and π-Josephson junctions (JJs), called π-SQUID, is studied by the resistively shunted junction model. The π-SQUID shows half-integer Shapiro-steps (SS) under microwave irradiation at the voltage V = ( ℏ / 2 e ) Ω ( n / 2 ) , with angular frequency Ω and half-integer n/2 in addition to integer n. We show that the π-SQUID can be a π-qubit with spontaneous loop currents by which the half-integer SS are induced. Making the 0- and π-JJs equivalent is a key for the half-integer SS and realizing the π-qubit.

arXiv:2108.11006•Applied Physics Express•Aug 25, 2021•2 citations

Model analysis for a current-step-like structure in a high Tc Josephson device coupled to a microwave signal

Yoshinao Mizugaki, Jian Chen

High Tc Josephson junctions have IcRn products as large as a few mV at liquid helium temperature, and hence, the frequency normalized by IcRn∕Φ0 becomes on the order of 10−3 for a gigahertz (GHz) microwave signal. (Here, Ic, Rn, and Φ0 are the critical current, the normal resistance, and a flux quantum, respectively.) It is well known that a microwave-current-driven Josephson junction does not exhibit clear Shapiro steps under such low frequency conditions. Instead of Shapiro steps, however, we often observe a current-step-like structure in the current–voltage curve of YBa2Cu3O7−δ grain boundary Josephson junctions coupled to a GHz signal. In this article, we present a model analysis for such current-step-like structures. Two types of device models are employed: a simple resistively and capacitively shunted junction model and a rf-field-driven two-junction superconducting quantum interference device model. Numerical results of the latter model agree with the experimental results, which indicates that the envelope of small Shapiro steps, including the effects of microwave-induced motion of flux quanta, appears as a current-step-like structure in a high Tc Josephson device coupled to a GHz microwave.

Journal of Applied Physics•Mar 8, 2005•3 citations

Zero-Crossing Shapiro Step in Asymmetric Two-Junction Superconducting Quantum Interference Device

Yoshinao Mizugaki, Kazuyuki Katoh, Masataka Moriya +2 more

We demonstrate a zero-crossing Shapiro step in an asymmetric two-junction superconducting quantum interference device (SQUID) driven by one sinusoidal RF signal. The operation is based on the imbalanced evolution of the junction phases due to the tilted interference diagrams. A test circuit was fabricated using Nb/AlO x /Nb junction technology. When we applied an RF signal of 10 GHz, we observed a Shapiro step crossing the zero-current axis at the voltage position of the first order. The polarity of the step voltage was switched by a DC control flux to the SQUID loop. The experimental current–voltage curves were quantitatively reproduced by simulation.

Japanese Journal of Applied Physics•Jun 16, 2006•3 citations

Zero-crossing Shapiro step generated in an asymmetric and nonhysteretic rf-current-driven two-junction superconducting quantum interference device

Yoshinao Mizugaki, Kazuyuki Katoh

A zero-crossing Shapiro step (ZCSS) in an asymmetric and nonhysteretic two-junction superconducting quantum interference device (SQUID) driven by one sinusoidal rf signal is presented. The operation is based on imbalanced evolution of the junction phases owing to the tilted interference diagrams. Dependence of ZCSS generation upon the frequency and amplitude of a rf signal was numerically obtained. A test circuit was designed and fabricated using a Nb∕AlOx∕Nb junction technology. When we irradiated a rf signal of 10GHz, a ZCSS at the voltage position of the first order was observed. The polarity of the step voltage was switched by a dc control flux to the SQUID loop. The experimental bias-current versus voltage and control-current versus voltage curves were quantitatively reproduced by numerical simulation.

Journal of Applied Physics•Sep 15, 2006•6 citations

The internal Shapiro effect in some portions of the parameter space of asymmetric two-junction SQUIDs and its influences

Mohammad Eatesami

The Shapiro effect is known, with regular steps in the voltage–current characteristic of a Josephson junction in the presence of microwave radiation, and so are its applications. In asymmetric two-junction SQUIDs (superconducting quantum interference devices), in particular the interactions between various current contributions in the two junctions lead to more varied and richer conditions. In this paper, we discuss the possibility and the impacts of a kind of internal Shapiro effect in some portions of the parameter space of the asymmetric high-TC SQUID with overdamped junctions and large loop inductance. In this predicted phenomenon, the required high-frequency radiation is produced spontaneously in the interior of the SQUID. The main message is the importance of achieving a set of nine parameters for the device whose voltage–current characteristics show no indication of spike–step-like structures.

Superconductor Science and Technology•Jun 13, 2013•0 citations
A high-Tc dc superconducting quantum interference device (SQUID) with three Josephson junctions (JJs) in series in each of its arms has been fabricated. Its Shapiro steps were studied using microwave (rf) radiation of 10 GHz and weak magnetic fields. The appearance of giant Shapiro steps and of some of half-integer steps was observed. Separation between the adjacent Shapiro steps could be tuned by rf magnetic fields and small external dc magnetic fields. This phenomenon was analyzed by phase locking the JJs in the SQUID.
Integer and half-integer Shapiro step amplitudes in the current-voltage characteristics of symmetric superconducting quantum interference devices (SQUIDS), containing more than one Josephson junction on each arm, are analytically calculated for small values of the parameter β and in the absence of noise. This analysis is made possible by the reduction of the dynamical equations of the multiple-junction SQUID to the dynamical equation of a single Josephson junction possessing a nonconventional current-phase relation.
Abstract A superconducting quantum interference device (SQUID) comprising 0- and π-Josephson junctions (JJs), called π-SQUID, is studied by the resistively shunted junction model. The π-SQUID shows half-integer Shapiro-steps (SS) under microwave irradiation at the voltage V = ( ℏ / 2 e ) Ω ( n / 2 ) , with angular frequency Ω and half-integer n/2 in addition to integer n. We show that the π-SQUID can be a π-qubit with spontaneous loop currents by which the half-integer SS are induced. Making the 0- and π-JJs equivalent is a key for the half-integer SS and realizing the π-qubit.
High Tc Josephson junctions have IcRn products as large as a few mV at liquid helium temperature, and hence, the frequency normalized by IcRn∕Φ0 becomes on the order of 10−3 for a gigahertz (GHz) microwave signal. (Here, Ic, Rn, and Φ0 are the critical current, the normal resistance, and a flux quantum, respectively.) It is well known that a microwave-current-driven Josephson junction does not exhibit clear Shapiro steps under such low frequency conditions. Instead of Shapiro steps, however, we often observe a current-step-like structure in the current–voltage curve of YBa2Cu3O7−δ grain boundary Josephson junctions coupled to a GHz signal. In this article, we present a model analysis for such current-step-like structures. Two types of device models are employed: a simple resistively and capacitively shunted junction model and a rf-field-driven two-junction superconducting quantum interference device model. Numerical results of the latter model agree with the experimental results, which indicates that the envelope of small Shapiro steps, including the effects of microwave-induced motion of flux quanta, appears as a current-step-like structure in a high Tc Josephson device coupled to a GHz microwave.
We demonstrate a zero-crossing Shapiro step in an asymmetric two-junction superconducting quantum interference device (SQUID) driven by one sinusoidal RF signal. The operation is based on the imbalanced evolution of the junction phases due to the tilted interference diagrams. A test circuit was fabricated using Nb/AlO x /Nb junction technology. When we applied an RF signal of 10 GHz, we observed a Shapiro step crossing the zero-current axis at the voltage position of the first order. The polarity of the step voltage was switched by a DC control flux to the SQUID loop. The experimental current–voltage curves were quantitatively reproduced by simulation.
A zero-crossing Shapiro step (ZCSS) in an asymmetric and nonhysteretic two-junction superconducting quantum interference device (SQUID) driven by one sinusoidal rf signal is presented. The operation is based on imbalanced evolution of the junction phases owing to the tilted interference diagrams. Dependence of ZCSS generation upon the frequency and amplitude of a rf signal was numerically obtained. A test circuit was designed and fabricated using a Nb∕AlOx∕Nb junction technology. When we irradiated a rf signal of 10GHz, a ZCSS at the voltage position of the first order was observed. The polarity of the step voltage was switched by a dc control flux to the SQUID loop. The experimental bias-current versus voltage and control-current versus voltage curves were quantitatively reproduced by numerical simulation.
The Shapiro effect is known, with regular steps in the voltage–current characteristic of a Josephson junction in the presence of microwave radiation, and so are its applications. In asymmetric two-junction SQUIDs (superconducting quantum interference devices), in particular the interactions between various current contributions in the two junctions lead to more varied and richer conditions. In this paper, we discuss the possibility and the impacts of a kind of internal Shapiro effect in some portions of the parameter space of the asymmetric high-TC SQUID with overdamped junctions and large loop inductance. In this predicted phenomenon, the required high-frequency radiation is produced spontaneously in the interior of the SQUID. The main message is the importance of achieving a set of nine parameters for the device whose voltage–current characteristics show no indication of spike–step-like structures.