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

arXiv:2305.04442 · Communications in Theoretical Physics

Controlling a superconducting transistor by coherent light

Guo-Jian Qiao, Zhilei Zhang, Sheng-Wen Li, Chang-Pu Sun

Published Mar 27, 2025• 1 citation
arXivHTMLPDF

Abstract

Abstract The Josephson junction is typically tuned by a magnetic field or electrostatic gate to realize a superconducting (SC) transistor, which manipulates the supercurrent in integrated SC circuits. Here, we propose a theoretical scheme for a light-controlled SC transistor, which is composed of two superconductor leads weakly linked by a coherent light-driven quantum dot. We discover a Josephson-like relation for the supercurrent I s = I c ( Φ ) sin Φ , where both the supercurrent phase Φ and magnitude I c can be completely controlled by the phase, intensity, and detuning of the driving light. Additionally, the supercurrent magnitude displays a Fano profile with the increase of the driving light intensity, which is understood by comparing the level splitting of the quantum dot under light driving with the SC gap. Moreover, when two such SC transistors form a loop, they constitute a light-controlled SC quantum interference device (SQUID). Such a light-controlled SQUID can demonstrate the Josephson diode effect, and the optimized non-reciprocal efficiency achieves up to 54%, surpassing the maximum record reported in recent literature. Thus, our scheme delivers a promising platform for performing diverse and flexible manipulations in SC circuits.

DOI
10.1088/1572-9494/adc5e8

Related papers

High-efficiency superconducting diode effect in a gate-tunable double-loop SQUID

Wyatt Gibbons, Teng Zhang, Kevin Barrow +3 more

In superconducting quantum interference devices (SQUIDs), the superconducting diode effect may be generated by interference of multiple harmonic components in the current-phase relationships (CPRs) of different branches forming SQUID loops. Through the inclusion of two gate-tunable Josephson junctions in series in each interference branch of a double-loop SQUID, we demonstrate independent control over both the harmonic content and the amplitude of three interfering CPRs, facilitating significant improvement in the maximum diode efficiency. Through optimized gate-controlled tuning of individual Josephson energies, diode efficiency exceeding 50% is demonstrated. Flux-dependent oscillations show quantitative agreement with a simple model of SQUID operation.

arXiv:2512.14909•Physical review. B./Physical review. B•Apr 6, 2026•1 citation

Double loop dc-SQUID as a tunable Josephson diode

Angelo Greco, Q. Pichard, Elia Strambini +1 more

The development of superconducting electronics requires careful characterization of the components that makeup electronic circuits. Superconducting weak links are the building blocks of most superconducting electronic components and are characterized by highly nonlinear current-to-phase relations (CPRs), which are often not perfectly known. Recent research has found that the Josephson diode effect (JDE) can be related to the high harmonic content of the current-to-phase relation of the weak links embedded in superconducting interferometers. This makes the JDE a natural tool for exploring the harmonic content of weak links beyond single-harmonic CPR. In this study, we present the theoretical model and experimental characterization of a double-loop superconducting quantum interference device (DL-SQUID) that embeds all-metallic superconductor-normal metal-superconductor junctions. The proposed device exhibits the JDE due to the interference of the supercurrents of three weak links in parallel, and this feature can be adjusted through two magnetic fluxes, which act as experimental knobs. We carry out a theoretical study of the device in terms of the relative weight of the interferometer arms and the experimental characterization concerning flux tunability and temperature.

arXiv:2404.05521•Applied Physics Letters•Aug 12, 2024•13 citations

Local tunability in a multi-port SQUID by an injection current

Zuyu Xu, Wanghao Tian, Shixian Chen +12 more

Abstract The tunability in Josephson junctions is foundational to the superconducting classical and quantum applications. Here, we demonstrate the local manipulation of supercurrent realized in a superconducting quantum interference device (SQUID) with two Nb/TiO x /Nb Josephson junctions that is biased at the TiO x layer. Our measurements indicate that the multi-port device allows for an easy and in situ tunability of the supercurrent. The control mechanism can be finely explained by simple yet valid theoretical methods, which take an effective electronic temperature across the SQUID and the self inductive magnetic flux into account. Furthermore, we show that the phase difference and kinetic inductance of this device can be tuned locally via the injection current. Thus, the device provides perspective for several superconducting electronics such as tunable superconducting circuits, sensitive magnetometry, and fast digital elements.

Superconductor Science and Technology•Oct 19, 2021•3 citations

Bistable All-Josephson Junction SQUID with Dual Φ-Junctions for State-Controlled Superconducting Circuits

Ayisat Adedokun, Yerzhan Mustafa, Selçuk Köse

A bistable superconducting quantum interference device (SQUID) exclusively comprising Josephson junctions (JJs) is proposed. The design integrates two $2 \Phi$-JJs within the loop structure, while the state of the SQUID is monitored through a conventional $2 \pi$-periodic $\mathbf{J J}$ ($\mathbf{0}$-JJ). This configuration eliminates the need for geometric inductors, leveraging the nonlinear phase dynamics for bistability. Extensive simulations confirm robust bistable operation under controlled external flux bias, positioning the proposed SQUID as an area-efficient building block for superconducting memory cells, sensors for various applications, and SFQ-compatible logic elements.

IEEE Computer Society Annual Symposium on VLSI•Jul 6, 2025•1 citation

Anomalous Josephson current through a driven double quantum dot

Carlos Ortega-Taberner, Antti‐Pekka Jauho, Jens Paaske

Josephson junctions based on quantum dots offer a convenient tunability by means of local gates. Here we analyze a Josephson junction based on a serial double quantum dot in which the two dots are individually gated by phase-shifted microwave tones of equal frequency. We calculate the time-averaged current across the junction and determine how the phase shift between the drives modifies the current-phase relation of the junction. Breaking particle-hole symmetry on the dots is found to give rise to a finite average anomalous Josephson current with phase bias between the superconductors fixed to zero. This microwave gated weak link thus realizes a tunable ``Floquet ${\ensuremath{\varphi}}_{0}$ junction'' with maximum critical current achieved for driving frequencies slightly off resonance with the subgap excitation energy. We provide numerical results supported by an analytical analysis for infinite superconducting gap and weak interdot coupling. We identify an interaction-driven $0\text{\ensuremath{-}}\ensuremath{\pi}$ transition of anomalous Josephson current as a function of driving phase difference. Finally, we show that this junction can be tuned so as to provide for complete rectification of the time-averaged Josephson current-phase relation.

arXiv:2207.06152•Physical review. B./Physical review. B•Mar 29, 2023•22 citations

Gate- and flux-tunable sin(2φ) Josephson element with planar-Ge junctions

Axel Leblanc, Chotivut Tangchingchai, Zahra Sadre Momtaz +11 more

Abstract Hybrid superconductor-semiconductor Josephson field-effect transistors (JoFETs) function as Josephson junctions with a gate-tunable critical current. Additionally, they can feature a non- sinusoidal current-phase relation (CPR) containing multiple harmonics of the superconducting phase difference, a so-far underutilized property. In this work, we exploit this multi-harmonicity to create a Josephson circuit element with an almost perfectly π-periodic CPR, indicative of a largely dominant charge-4e supercurrent transport. Such a Josephson element was recently proposed as the basic building block of a protected superconducting qubit. Here, it is realized using a superconducting quantum interference device (SQUID) with low-inductance aluminum arms and two nominally identical JoFETs. The latter are fabricated from a SiGe/Ge/SiGe quantum-well heterostructure embedding a high-mobility two-dimensional hole gas. By carefully adjusting the JoFET gate voltages and finely tuning the magnetic flux through the SQUID close to half a flux quantum, we achieve a regime where the sin(2φ) component accounts for more than 95 % of the total supercurrent. This result demonstrates a new promising route for the realization of superconducting qubits with enhanced coherence properties.

arXiv:2405.14695•Nature Communications•Jan 24, 2025•16 citations
Abstract The Josephson junction is typically tuned by a magnetic field or electrostatic gate to realize a superconducting (SC) transistor, which manipulates the supercurrent in integrated SC circuits. Here, we propose a theoretical scheme for a light-controlled SC transistor, which is composed of two superconductor leads weakly linked by a coherent light-driven quantum dot. We discover a Josephson-like relation for the supercurrent I s = I c ( Φ ) sin Φ , where both the supercurrent phase Φ and magnitude I c can be completely controlled by the phase, intensity, and detuning of the driving light. Additionally, the supercurrent magnitude displays a Fano profile with the increase of the driving light intensity, which is understood by comparing the level splitting of the quantum dot under light driving with the SC gap. Moreover, when two such SC transistors form a loop, they constitute a light-controlled SC quantum interference device (SQUID). Such a light-controlled SQUID can demonstrate the Josephson diode effect, and the optimized non-reciprocal efficiency achieves up to 54%, surpassing the maximum record reported in recent literature. Thus, our scheme delivers a promising platform for performing diverse and flexible manipulations in SC circuits.
In superconducting quantum interference devices (SQUIDs), the superconducting diode effect may be generated by interference of multiple harmonic components in the current-phase relationships (CPRs) of different branches forming SQUID loops. Through the inclusion of two gate-tunable Josephson junctions in series in each interference branch of a double-loop SQUID, we demonstrate independent control over both the harmonic content and the amplitude of three interfering CPRs, facilitating significant improvement in the maximum diode efficiency. Through optimized gate-controlled tuning of individual Josephson energies, diode efficiency exceeding 50% is demonstrated. Flux-dependent oscillations show quantitative agreement with a simple model of SQUID operation.
The development of superconducting electronics requires careful characterization of the components that makeup electronic circuits. Superconducting weak links are the building blocks of most superconducting electronic components and are characterized by highly nonlinear current-to-phase relations (CPRs), which are often not perfectly known. Recent research has found that the Josephson diode effect (JDE) can be related to the high harmonic content of the current-to-phase relation of the weak links embedded in superconducting interferometers. This makes the JDE a natural tool for exploring the harmonic content of weak links beyond single-harmonic CPR. In this study, we present the theoretical model and experimental characterization of a double-loop superconducting quantum interference device (DL-SQUID) that embeds all-metallic superconductor-normal metal-superconductor junctions. The proposed device exhibits the JDE due to the interference of the supercurrents of three weak links in parallel, and this feature can be adjusted through two magnetic fluxes, which act as experimental knobs. We carry out a theoretical study of the device in terms of the relative weight of the interferometer arms and the experimental characterization concerning flux tunability and temperature.
Abstract The tunability in Josephson junctions is foundational to the superconducting classical and quantum applications. Here, we demonstrate the local manipulation of supercurrent realized in a superconducting quantum interference device (SQUID) with two Nb/TiO x /Nb Josephson junctions that is biased at the TiO x layer. Our measurements indicate that the multi-port device allows for an easy and in situ tunability of the supercurrent. The control mechanism can be finely explained by simple yet valid theoretical methods, which take an effective electronic temperature across the SQUID and the self inductive magnetic flux into account. Furthermore, we show that the phase difference and kinetic inductance of this device can be tuned locally via the injection current. Thus, the device provides perspective for several superconducting electronics such as tunable superconducting circuits, sensitive magnetometry, and fast digital elements.
A bistable superconducting quantum interference device (SQUID) exclusively comprising Josephson junctions (JJs) is proposed. The design integrates two 2Φ2 \Phi2Φ-JJs within the loop structure, while the state of the SQUID is monitored through a conventional 2π2 \pi2π-periodic JJ\mathbf{J J}JJ (0\mathbf{0}0-JJ). This configuration eliminates the need for geometric inductors, leveraging the nonlinear phase dynamics for bistability. Extensive simulations confirm robust bistable operation under controlled external flux bias, positioning the proposed SQUID as an area-efficient building block for superconducting memory cells, sensors for various applications, and SFQ-compatible logic elements.
Josephson junctions based on quantum dots offer a convenient tunability by means of local gates. Here we analyze a Josephson junction based on a serial double quantum dot in which the two dots are individually gated by phase-shifted microwave tones of equal frequency. We calculate the time-averaged current across the junction and determine how the phase shift between the drives modifies the current-phase relation of the junction. Breaking particle-hole symmetry on the dots is found to give rise to a finite average anomalous Josephson current with phase bias between the superconductors fixed to zero. This microwave gated weak link thus realizes a tunable ``Floquet ${\ensuremath{\varphi}}_{0}$ junction'' with maximum critical current achieved for driving frequencies slightly off resonance with the subgap excitation energy. We provide numerical results supported by an analytical analysis for infinite superconducting gap and weak interdot coupling. We identify an interaction-driven $0\text{\ensuremath{-}}\ensuremath{\pi}$ transition of anomalous Josephson current as a function of driving phase difference. Finally, we show that this junction can be tuned so as to provide for complete rectification of the time-averaged Josephson current-phase relation.
Abstract Hybrid superconductor-semiconductor Josephson field-effect transistors (JoFETs) function as Josephson junctions with a gate-tunable critical current. Additionally, they can feature a non- sinusoidal current-phase relation (CPR) containing multiple harmonics of the superconducting phase difference, a so-far underutilized property. In this work, we exploit this multi-harmonicity to create a Josephson circuit element with an almost perfectly π-periodic CPR, indicative of a largely dominant charge-4e supercurrent transport. Such a Josephson element was recently proposed as the basic building block of a protected superconducting qubit. Here, it is realized using a superconducting quantum interference device (SQUID) with low-inductance aluminum arms and two nominally identical JoFETs. The latter are fabricated from a SiGe/Ge/SiGe quantum-well heterostructure embedding a high-mobility two-dimensional hole gas. By carefully adjusting the JoFET gate voltages and finely tuning the magnetic flux through the SQUID close to half a flux quantum, we achieve a regime where the sin(2φ) component accounts for more than 95 % of the total supercurrent. This result demonstrates a new promising route for the realization of superconducting qubits with enhanced coherence properties.