SQUID Architectures: From DC Loops to Topological Junctions

Superconducting Quantum Interference Devices are superconducting loops interrupted by one or more Josephson junctions — devices in which a thin insulating or normal-metal barrier separates two superconducting electrodes. Magnetic flux threading the loop modulates the critical current and voltage response, enabling detection of magnetic fields far below the femtotesla threshold. This dataset spans six distinct SQUID sub-architectures, each occupying a different position on the maturity curve.

DC SQUIDs remain the workhorse architecture, using two Josephson junctions in a superconducting loop. A study from the University of Tübingen reports that asymmetrically shunted Nb/Al-AlOx/Nb dc-SQUIDs achieve energy resolution ε ≈ 32ℏ — a factor of 3–4 improvement over symmetric designs — by differentially shunting only one of the two junctions. This confirms that resistor geometry is a non-trivial performance lever that has historically been underexplored.

RF SQUIDs use a single Josephson junction coupled inductively to an RF tank circuit. A 1999 patent from Yokogawa Electric Corporation describes fabrication of an RF SQUID with a Josephson junction and strip-line on a superconducting thin-film ground plane, designed for high reliability and reproducibility — an early signal of industrial uptake that preceded the quantum computing era by more than a decade.

SQUID arrays and Superconducting Quantum Interference Filters (SQUIFs) scale performance by coupling large numbers of loops. CSIRO holds the dominant patent estate in this architecture, with filings active across IL, SG, EP, and JP jurisdictions through 2025. Counter-intuitively, CSIRO’s invention demonstrates that restricting parallel loops per row to between 2 and 20 — rather than maximizing them — improves performance, a finding that runs against conventional wisdom and has been prosecuted across at least six jurisdictions.

Topological SQUIDs represent the most nascent sub-domain. A study from Sandia National Laboratories reports microwave response measurements in a SQUID realized in the Dirac semimetal Cd₃As₂, opening paths toward topological single-photon detection at microwave frequencies. The Differential Double Contour Interferometer (DDCI), introduced by the Institute of Microelectronics Technology at the Russian Academy of Sciences in 2017, proposes two superconducting contours weakly coupled by Josephson junctions as a potential competitor to traditional SQUIDs for ultrasensitive flux detection and qubit readout.

A comprehensive 2018 review from Forschungszentrum Jülich places SQUIDs within the full superconductor circuit stack — Josephson junctions, oscillators, passive transmission lines, resonators, and cryogenic enclosures — noting applications from voltage standards and astronomy detectors to magnetoencephalography and materials characterization. According to WIPO, superconducting electronics patents have grown consistently over the past decade as quantum computing investment has accelerated globally.

Who Owns the IP: Assignee and Jurisdiction Concentration

CSIRO is the single most prolific SQUID assignee in this dataset, with at least 7 active patent family members across IL, SG, EP, and JP jurisdictions, all derived from a 2018 Australian provisional application (AU2018901053). Japan has emerged as the dominant foreign prosecution jurisdiction, with at least 8 filings from IBM, Huawei, Tencent, Oxford University Innovation, and CSIRO — a concentration that reflects the importance of the Japanese market for quantum computing hardware and IP enforcement strategy.

IBM Corporation entered with two notable patents: a 2023 JP filing on vertical silicon-on-metal SQUIDs integrating Josephson junctions into a crystalline silicon-on-metal substrate, and a 2024 JP grant on gradiometric parallel SQUIDs for qubit frequency fine-tuning. These signal large-scale semiconductor-process integration as the frontier as of 2023–2025. Oxford University Innovation holds two JP-jurisdiction active patents (2023, 2025) on superconducting quantum computing circuit packages with electromagnetic mode suppression.

Huawei Technologies’ 2025 JP patent on superconducting quantum chip architecture with SQUID-based coupling elements is the most recent filing in this dataset, signalling Chinese technology firm entry into SQUID-adjacent quantum hardware IP. Tencent Technology (Shenzhen) holds one JP-jurisdiction active patent (2023) on a superconducting quantum hybrid system with silicon carbide epitaxial substrates and nitrogen-vacancy centers. Consiglio Nazionale delle Ricerche (Italian National Research Council) holds the only European-national office prosecution in the dataset: a pending IT-jurisdiction patent on a superconducting interferometer (2023). According to EPO filing statistics, quantum technology patent applications have been among the fastest-growing technology categories in Europe over the past five years.

“Organizations without JP prosecution strategies for SQUID and superconducting circuit IP risk ceding market access in a jurisdiction where Huawei, Tencent, IBM, Oxford University Innovation, and CSIRO are all active.”

Literature contributions in this dataset are geographically broader, with significant representation from the USA (NIST, MIT Lincoln Laboratory, Sandia National Laboratories, Caltech, JILA), Germany (Forschungszentrum Jülich, University of Tübingen), Netherlands (SRON), Italy (NEST Istituto Nanoscienze-CNR, INFN), Russia (Russian Academy of Sciences), Australia (CSIRO, University of Technology Sydney), and China (Tsinghua University, Chinese Academy of Sciences, USTC). The earliest patent in the dataset is a 1971 filing by Ford Motor Co. (DE jurisdiction, now inactive) describing a quantum interferometer using a superconductive plate — a thin-film ohmic metal strip bridging two superconducting contact areas.

Application Domains Driving SQUID Innovation in 2026

The largest cluster of recent SQUID activity connects directly to superconducting qubit systems — SQUIDs serve as both tunable inductors for qubit frequency adjustment and as readout amplifiers in quantum processors. This dual role makes SQUID design inseparable from quantum processor architecture, a convergence that IBM’s recent patent filings make explicit.

Quantum Computing and Qubit Control

IBM’s gradiometric and vertical SQUID patents are explicitly targeted at frequency fine-tuning and noise suppression in qubit circuits. JILA (University of Colorado) proposes an on-chip superconducting microwave circulator based on dynamically modulated dc-SQUIDs as tunable inductors, offering a chip-integrated alternative to off-chip ferrite circulators. Huawei Technologies’ 2025 JP patent on superconducting quantum chips uses coupler circuits — implicitly SQUID-based — to eliminate crosstalk via phase inversion point control between qubit frequencies. NIST (Boulder) demonstrates lumped-element dc-SQUID amplifiers with noise temperature below 1 K (three photons of added noise) in the 4–8 GHz band, providing the amplification gain for qubit readout chains.

Space-Borne X-ray and Millimetre-Wave Astronomy

SQUIDs are the enabling readout technology for large Transition Edge Sensor (TES) microcalorimeter and bolometer arrays on planned and proposed space missions. SRON Netherlands Institute for Space Research describes a 3,840-pixel TES array for ESA’s Athena X-IFU instrument, read out via Frequency Domain Multiplexing (FDM) using SQUIDs. Tsinghua University’s Low Temperature Detector Laboratory describes superconducting microcalorimeter development for the HUBS space X-ray mission. The Forschungszentrum Jülich review (2018) specifically lists “astronomy detectors and large telescope cameras” among the most commercially successful current SQUID applications. According to ESA, the Athena mission is currently scheduled for launch in the 2030s, creating a near-term government procurement opportunity for SQUID multiplexer chipsets qualified for cryogenic space environments.

Broadband RF Signal Processing

Hypres, Inc.’s Superconducting Quantum Array (SQA) work using Differential Quantum Cells (DQCs) achieves approximately 100 mV peak-to-peak voltage swing and steepness of approximately 6,500 µV/µT in niobium process fabrication — performance figures relevant to high-dynamic-range RF signal reception and electrically small antenna applications. CSIRO’s SQUIF array patents also target this domain. The University of Technology Sydney’s 2022 overview of high-temperature superconducting microwave devices highlights SQUID Josephson junction active components integrated into receiver front-ends and monolithic microwave integrated circuits (MMICs) with cryocooler integration.

Microwave Single-Photon Detection and Fundamental Physics

Sandia National Laboratories’ topological SQUID study (Cd₃As₂ Dirac semimetal, 2021) and Italy’s INFN SIMP project (2020) developing Josephson junction-based detectors for the 10–50 GHz range both point to SQUIDs and SQUID-related devices as leading candidates for microwave photon-number-resolving detection — a critical missing tool for quantum information science. A 2017 paper from the Institute of Theoretical Physics, University of Warsaw, proposes a dc-SQUID-based transmission line as an analog simulator of quantum fields in an expanding universe, while a 2015 University of Nottingham study uses SQUID-modulated superconducting waveguides to generate Einstein-Podolsky-Rosen steering via the dynamical Casimir effect.

Emerging Technical Directions and Pre-Competitive Frontiers

Five distinct emerging directions are identifiable from filings and publications dated 2021 onward in this dataset, ranging from semiconductor process convergence to topological materials and wafer-scale routing platforms.

1. SQUID Integration into Semiconductor Fab Processes (2023–2024)

IBM’s vertical silicon-on-metal SQUID (JP, 2023) and gradiometric SQUID (JP, 2024) represent the clearest signal that SQUID manufacturing is converging with CMOS-compatible processes. The vertical design places Josephson junction vias between superconducting layers separated by crystalline silicon, enabling SQUID loops in a fully planar 3D geometry compatible with CMOS-adjacent fabrication. The gradiometric design is specifically optimized to suppress common-mode magnetic noise while enabling fine-tuning of qubit frequencies — a key requirement for scaled quantum processors. IBM’s SQUID design is becoming embedded in standard quantum processor IP rather than treated as standalone sensing IP.

2. Topological Materials as SQUID Substrates (2021)

Sandia National Laboratories’ study of SQUIDs in the Dirac semimetal Cd₃As₂ opens a materials frontier where topological protection may suppress decoherence mechanisms that limit conventional Nb or Al-based SQUIDs. The observed large microwave response in this system is described as a potential path toward topological single-photon counting. Early IP positioning in topological SQUID materials faces minimal current competition based on this dataset, making it a high-reward pre-competitive opportunity.

3. SQUID-Enabled 3D Superconducting Routing Platforms (2022)

A University of Grenoble Alpes study describes multi-layer superconducting routing platforms on 200 mm silicon wafers using TiN, Nb, and NbN layers connected by tungsten vias, designed to hybridize spin qubit chips with control electronics. SQUIDs are implicit components in the readout chains of such platforms, signalling that SQUID technology must scale to wafer-level manufacturing — a fabrication challenge that aligns directly with the semiconductor process convergence described above.

4. Chinese Technology Firms Entering SQUID-Adjacent Hardware IP (2023–2025)

Tencent (2023) and Huawei (2025) patents in JP jurisdiction on superconducting quantum chips using SQUID-based coupling and hybrid solid-state/superconducting architectures indicate that Chinese technology firms are building foundational quantum hardware IP estates — including SQUID-related elements — through major foreign filing strategies. Huawei’s 2025 filing is the most recently dated patent in this entire dataset, underscoring the pace of Chinese entry into this space. The OECD has documented a sustained increase in Chinese quantum technology patent filings in foreign jurisdictions since 2018.

5. CSIRO’s SQUIF Array Patent Family Reaching EP Grant (2025)

The grant of CSIRO’s SQUIF array patent in the European Patent Office (EP, September 2025) — the most recently dated patent in this dataset — signals that the array performance optimization architecture is achieving broad international protection. Competitors building RF sensor or quantum readout products in Europe will need to design around this family. The key counter-intuitive claim — that restricting parallel loops per row to between 2 and 20 improves performance — is now protected in EP, IL, SG, and JP jurisdictions simultaneously.

Strategic Implications for IP and R&D Teams

CSIRO’s SQUIF array patent family constitutes the dominant IP barrier in high-sensitivity SQUID array design. Any organization developing large-format SQUID arrays for RF sensing, quantum computer readout, or astronomy instrumentation operating in IL, SG, EP, or JP must conduct freedom-to-operate analysis against this family before product development. The family derives from a 2018 Australian provisional application (AU2018901053) and is active across at least six jurisdictions with the EP grant confirmed in September 2025.

IBM’s vertical and gradiometric SQUID patents signal that SQUID design is becoming embedded in standard quantum processor IP, not treated as standalone sensing IP. R&D teams building scalable superconducting quantum computers should anticipate that SQUID-based tuning and readout elements will be increasingly claimed as part of broader qubit architecture patents. This convergence — documented by USPTO in its quantum computing patent classification updates — makes it essential to monitor both quantum computing and sensing patent classes simultaneously.

The topological SQUID direction (Dirac semimetals, 2021) is pre-competitive but high-reward. If noise performance in topological Josephson junctions matures, it could disrupt the dominance of Nb-based device platforms. Early IP positioning in topological SQUID materials (Cd₃As₂, other topological semimetals) faces minimal current competition based on this dataset. Organizations active in materials science and quantum sensing should consider whether this represents a viable white-space opportunity.

For quantum computing hardware manufacturers, the SQUIPT architecture from NEST Istituto Nanoscienze-CNR and University of Tabriz achieves flux-to-voltage transfer functions up to 3 mV/Φ₀ and flux-to-current transfer exceeding 100 nA/Φ₀ in aluminum-copper devices — performance figures that, combined with micrometer-scale dimensions and ultralow dissipation (flux noise ~10⁻⁵ Φ₀Hz⁻¹/²), make SQUIPTs attractive for magnetization studies of nanoscale samples and sub-kelvin quantum sensing applications.

“Restricting parallel loops per row to between 2 and 20 — rather than maximizing them — improves SQUID array performance. This counter-intuitive finding is now protected across EP, IL, SG, and JP jurisdictions simultaneously.”

The Hypres SQA/DQC architecture achieving approximately 6,500 µV/µT steepness in niobium process fabrication represents a commercially validated benchmark for broadband RF applications. Organizations developing electrically small antenna receivers or electronic warfare front-ends should benchmark their SQUID-based designs against this figure and assess whether Hypres holds relevant IP in their target markets. The full superconductor electronics ecosystem context — including passive transmission lines, resonators, and cryogenic enclosures — is mapped comprehensively in the Forschungszentrum Jülich review (2018), which remains the most authoritative single-source overview in this dataset. For a broader view of the global patent landscape across all quantum technologies, PatSnap’s innovation intelligence resources and IP intelligence solutions provide structured analysis across multiple technology domains.