Superconducting qubit chips: junctions, wafers and bump bonds
See what sits on a transmon qubit chip, why most makers fabricate their own, which foundries are joining in, and where tools, wafers and materials come in.
A silicon die patterned with about a hundred superconducting transmon qubits, the tunable couplers between them and a readout resonator for each. The quantum state lives in these circuits.
What is on a superconducting qubit chip?
Superconducting circuits patterned on a low-loss substrate. Each transmon qubit is a pair of superconducting electrodes joined by a Josephson junction, conventionally made of aluminum, and Japan’s 2025 supply-chain roadmap names dielectric loss at the substrate and its interfaces, and radiation from the package, among the limits on how long qubits stay coherent. Tunable couplers link neighbors and a resonator reads each qubit: IBM’s Nighthawk joins 120 qubits with 218 tunable couplers in a square lattice, and Google’s Willow has 105 qubits. Larger chips go 3D. QuTech’s 2026 flip-chip transmons, bonded face-down to a second chip with electroplated indium bumps, reached quality factors around a million; AWS’s Ocelot prototype stacks two bonded chips of about 1 cm² each; and Rigetti bonds chiplets in house.
Who fabricates qubit chips?
Mostly the makers themselves. IBM makes its wafers at a 300 mm facility in Albany, where its company Anderon runs a pure-play quantum wafer foundry backed by a $1 billion CHIPS award; Google built Willow in its own Santa Barbara fab; Rigetti runs Fab-1 and sells 9-qubit Novera QPUs to others; IQM fabricates, packages and 3D-integrates its chips on 200 mm wafers; and Fujitsu developed its 256-qubit chip with RIKEN. D-Wave designs its circuits and has its wafers made by SkyWater, which IonQ has owned since July 31, 2026. Foundries are arriving: GlobalFoundries launched a quantum business in May 2026 whose superconducting QPU process is still in development, and STMicroelectronics fabricates Quobly’s silicon spin-qubit chips, a different device. QuantWare, Oxford Quantum Circuits and Qolab are private, and no listed maker reports chip revenue separately.
Which tools, wafers and materials sit upstream?
Tool makers document quantum work without breaking out sales. Rigetti bought an Oxford Instruments atomic-layer etch system for Fab-1 in May 2026, and NYU Nanofab installed Oxford Instruments’ ALD tool for superconducting nitrides; Qolab’s DARPA consortium names Applied Materials for materials development and wafer-level fabrication; and Veeco lists quantum computing among the uses of its ALD and MBE systems. Published recipes also name private tools, such as Plassys evaporators and Raith e-beam writers. For substrates, QuTech’s 2026 qubits started from >20 kΩ·cm silicon sourced from Topsil, part of GlobalWafers, and Kyocera researchers published superconducting vias through sapphire in 2024. Silicon-28 serves spin qubits instead: Soitec supplied Quobly’s first 28Si FD-SOI wafers, and Silex finished building an enrichment plant in June 2026, with commissioning due late 2026. These are research or prototype links, not disclosed volume supply.
How to research a qubit-chip company
Name the qubit type first: transmon chips, silicon spin-qubit chips and photonic chips come from different processes, so Quobly’s foundry and wafer partners, Silex and Intel’s Tunnel Falls serve spin qubits, not the illustrated transmons.
Separate in-house fabs from foundry customers: IBM, Google, Rigetti and IQM make their own chips, while D-Wave’s wafers come from SkyWater, now part of IonQ, which does not disclose whether that supply continues.
Read foundry news for its stage: GlobalFoundries’ superconducting process is in development, and Anderon names no external customers yet.
Treat recipe papers as research links: a lab naming its wafer, tool or indium supplier does not establish a supply relationship with a quantum-computer maker.
Check scale: Rigetti’s 2025 revenue was $7.1 million and IQM’s first-half 2026 revenue €8.9 million, while IBM, Alphabet and Amazon do not report quantum revenue.
Use the list as a starting point: it is curated, not exhaustive, and the model is illustrative, not a bill of materials.
A transmon is superconducting electrodes with a Josephson junction on a silicon substrate; dielectric loss at the substrate and interfaces and radiation from the package limit coherence.
A business to manufacture QPUs, cryogenic control and readout ICs and superconducting interconnects, with platforms in development for several qubit types.
Disclosed: IBM’s releases describe Nighthawk, Loon and its Albany 300 mm wafer fabrication, its quantum commitment and installed fleet, and Anderon’s CHIPS award.
Disclosed: D-Wave’s 2025 10-K, Q2 2026 10-Q and releases describe its in-house QPU design, SkyWater wafer supply, the Quantum Circuits acquisition, its roadmap and the CHIPS award.
Disclosed: IonQ’s Q2 2026 10-Q and results release give revenue, the 2025–2026 acquisitions and the SkyWater closing; D-Wave’s 2025 10-K names SkyWater as its wafer foundry.
Disclosed: GF’s May 2026 release launches Quantum Technology Solutions with quotes from PsiQuantum, Quantinuum, Diraq, Equal1 and Quantum Motion, and its Sept 2026 release finalizes the $375M award.
Disclosed: Intel’s newsroom describes Tunnel Falls and its 300 mm fabrication; Hitachi’s release (partner-disclosed) describes Intel’s 18A-based qubit process and PDK.
Disclosed: Oxford Instruments’ May 2026 releases name Rigetti and NYU Nanofab as users of its etch and deposition systems for quantum devices, and its FY2026 results report the NanoScience divestment.
Partner-disclosed: Qolab’s DARPA consortium release ties Applied Materials to materials and wafer-level fabrication for superconducting qubits, and HPE’s Quantum Scaling Alliance release lists it for materials engineering and semiconductor fabrication.
Partner-disclosed: QuTech’s 2026 flip-chip qubit paper names Topsil as the source of its high-resistivity silicon, and Topsil’s site places it in the GlobalWafers group.
Disclosed: a 2024 IEEE Transactions on Quantum Engineering paper by Kyocera researchers covers superconducting through-substrate vias on sapphire for quantum circuits.
Partner-disclosed: Quobly’s Dec 2025 release, with a quote from Soitec’s CTO, says Soitec provided the first custom 28Si FD-SOI wafers now cycling in ST’s 300 mm fab.
Disclosed: Silex’s Q-Si project page describes the silicon-28 plant, its June 2026 construction completion and SQC as initial offtake partner.
Also in this study (not publicly listed)
Anderon Subsidiary of IBM (IBM)
IBM’s 300 mm pure-play quantum wafer foundry in Albany for superconducting qubit arrays, quantum I/O and readout-chain components; finalized a $1 billion CHIPS award on Sept 16, 2026.
U.S. foundry that makes D-Wave’s superconducting QPU wafers under a semiconductor line operation agreement (D-Wave FY2025 10-K); its own FY2025 10-K says it supports superconducting, photonic and spin-based quantum customers. IonQ completed its acquisition on July 31, 2026 ($15.00 in cash plus 0.4883 IonQ shares per share) and SKYT was delisted; the role is mapped to IONQ.
Delft-based maker of superconducting QPUs (A-Line and D-Line) that also sells foundry services, VIO chiplet-packaging services and a Crescendo TWPA; its news page reports a $178M raise and Intel backing (Intel is an investor, not a stand-in).
Superconducting-qubit startup co-founded by John Martinis that leads hardware for an HPE-co-led DARPA Quantum Benchmarking Initiative consortium, with Applied Materials for materials and wafer-level fabrication.
French silicon spin-qubit maker whose QSOI chips are fabricated in STMicroelectronics’ 300 mm Crolles fab on Soitec 28Si FD-SOI wafers; raised a €115M Series A in June 2026 co-led by Bpifrance, SEALSQ and STMicroelectronics.
French maker of electron-beam evaporation systems; a University of Chicago and Stanford qubit recipe loads sapphire wafers into a Plassys MEB550S evaporator.
Topsil GlobalWafers A/S Subsidiary of GlobalWafers (6488.TWO)
Danish float-zone silicon maker in the GlobalWafers group (acquired July 1, 2016); QuTech’s 2026 flip-chip qubits used its >20 kΩ·cm wafers. GlobalWafers’ own listing covers the role.