The United Kingdom runs one of the deepest quantum-technology sectors outside the United States, built on decades of university research in Oxford, Cambridge and Bristol and backed by a National Quantum Strategy worth 2.5 billion pounds over ten years. That foundation is now producing real companies with real money behind them. In June 2026 alone, Oxford Quantum Circuits raised 260 million pounds, the largest quantum funding round Europe has yet seen.
This is our 2026 guide to fifteen UK quantum companies making waves across computing, security and sensing. We first published a version of this list in 2021, and the field has moved so fast since then that most of the original names have merged, been acquired or moved on. The companies below are grouped by what they build rather than ranked against each other, and every funding figure is tied to a company announcement, a university press office or a public filing.
1. Quantinuum
Quantinuum is the largest company on this list and the one with the deepest British roots. It was formed in November 2021 when Cambridge Quantum, which topped earlier versions of this guide as CQC, merged with Honeywell Quantum Solutions. The business now runs a dual headquarters across Cambridge and Colorado and is majority owned by Honeywell, so it is not a pure UK independent, yet its trapped-ion systems and TKET software carry a clear Cambridge lineage. In April 2026 it raised roughly 600 million dollars at a 10 billion dollar pre-money valuation, with Nvidia’s venture arm among the backers. Our full Quantinuum profile covers the company in more depth.
2. Oxford Ionics
Oxford Ionics built trapped-ion processors that run on standard silicon chips, steering the qubits with electronic control rather than the banks of lasers most ion machines need. The Oxford company became the sector’s biggest British exit when the American firm IonQ completed its acquisition on 17 September 2025 in a deal worth about 1.075 billion dollars. It now operates as IonQ’s UK subsidiary, and the parent has said it intends to expand the Oxford site rather than wind it down.
3. Riverlane
Riverlane, a 2016 spin-out from the University of Cambridge, works on the unglamorous but essential problem of quantum error correction. Its Deltaflow decoder stack is designed to catch and fix the errors that swamp today’s noisy machines, and it sells that technology to hardware makers rather than building a computer of its own. In August 2024 the company raised 75 million dollars in a Series C round that ranks among the largest investments dedicated to error correction anywhere.
4. Oxford Quantum Circuits
Oxford Quantum Circuits builds superconducting quantum computers around its Coaxmon design, a three-dimensional layout that places the control wiring above each qubit instead of beside it. Based at Thames Valley Science Park in Reading, the company delivers its machines both on-premises and through the cloud. In June 2026 it raised 260 million pounds, a round widely reported as the largest quantum funding ever closed in Europe.
5. Quantum Motion
Quantum Motion, spun out of University College London in 2017, is chasing scale by making qubits from the same silicon transistors that fill ordinary chips. That route would let it lean on the mature semiconductor supply chain rather than fabricate exotic hardware from scratch. The London company raised about 120 million pounds in a Series C round in May 2026.
6. ORCA Computing
ORCA Computing takes a photonic approach, using single photons at room temperature instead of the deeply chilled circuits most rivals depend on. That design keeps its PT-series machines small enough to slot into existing data centres and high-performance computing sites. In June 2025 ORCA installed a PT-2 system at the UK’s National Quantum Computing Centre, the first photonic quantum computer in the British public sector.
7. Universal Quantum
Universal Quantum, a University of Sussex spin-out, is building modular trapped-ion machines that link many small chips into one large computer through its UQ Connect interconnect. The company was selected for the Tech Nation Future Fifty 2026 cohort, and its chief executive has given evidence to Parliament on the technology. In December 2025 it agreed to work with the Atlas Copco Group on the extreme-vacuum systems that utility-scale ion traps demand.
8. Phasecraft
Phasecraft writes the algorithms that decide what a quantum computer actually does once it is switched on, aimed at problems in materials, chemistry and energy grids. The company keeps its methods hardware agnostic so they can run across different machines. Spun out of UCL and the University of Bristol, it raised 34 million dollars in a Series B round in September 2025.
9. Nu Quantum
Nu Quantum, another Cambridge spin-out, is tackling the wiring between quantum processors rather than the processors themselves. Its Entanglement Fabric is meant to link many QPUs into a single larger system, the quantum equivalent of networking servers in a data centre. In December 2025 the company raised 60 million dollars in a Series A led by National Grid Partners, the largest round yet for a pure quantum-networking firm.
10. PQShield
PQShield sits on the security side of the field, designing post-quantum cryptography that can withstand attack by a future quantum computer. Its researchers contributed to all three of the post-quantum encryption standards that the US National Institute of Standards and Technology finalised in August 2024. The Oxford company raised 37 million dollars in a Series B round in June 2024.
11. Arqit Quantum
Arqit Quantum, headquartered in London, sells a quantum-safe encryption platform built on symmetric keys and has traded on the Nasdaq since 2021. It is a genuine British operator, though its finances are tight, with full-year revenue still measured in hundreds of thousands of dollars and a heavy net loss reported for the first half of its 2026 financial year. Readers weighing its prospects should treat it as an early-stage business rather than an established one.
12. KETS Quantum Security
KETS Quantum Security, a University of Bristol spin-out, shrinks quantum key distribution and random-number generation onto silicon chips small enough for real networks. Working with BT under an Innovate UK contract, it completed a chip-based quantum key distribution prototype in April 2025. That kind of miniaturisation is exactly what quantum communication needs before it can leave the laboratory.
13. Quantum Dice
Quantum Dice, spun out of Oxford’s physics department in 2020, makes random-number generators that certify their own randomness using quantum measurements. Genuinely unpredictable numbers underpin strong encryption, and self-certification removes a common weak point. The company won a 2 million euro European Innovation Council grant in December 2025 and has since begun working with the air-traffic body NATS.
14. Delta.g
Delta.g, a 2023 spin-out from the University of Birmingham, builds quantum gravity sensors that read tiny changes in the local gravitational field. The devices can map pipes, tunnels and voids underground without any digging, and could one day support navigation where satellite signals fail. In September 2025 the Birmingham company closed an oversubscribed 4.6 million pound seed round.
15. Cerca Magnetics
Cerca Magnetics, based near Nottingham, turns quantum sensing into medical hardware with wearable brain scanners built from optically pumped magnetometers. Unlike a rigid conventional scanner, its system lets patients, including children, move their heads during a recording. In April 2026 Cerca raised a 3.8 million pound Series A that valued it at around 30 million pounds, and it is separately developing a mobile scanner with Ministry of Defence backing.
Other UK Quantum Companies Worth Watching
Fifteen names can only cover part of a crowded field of UK quantum companies. Sheffield’s Aegiq works on single-photon sources for photonic computing and networking, Bristol’s QLM Technology builds quantum gas cameras that spot methane leaks, and London’s Crypto Quantique secures connected devices with a post-quantum layer. The American hardware firm SEEQC also runs a substantial UK operation at Harwell, though its headquarters sit in New York.
One earlier entry is worth a correction. M Squared Lasers of Glasgow, which featured on previous versions of this list, entered administration in 2025, and its quantum and photonics assets passed to a newly formed company, Novacene Photonics. We have left it off the main list because the original trading entity no longer operates.
How We Chose These Companies
This guide favours businesses that are headquartered or heavily active in the United Kingdom, that work directly on quantum hardware, software, security or sensing, and that can point to a verifiable recent milestone. We have grouped them by what they do rather than ranking them, since a seed-stage sensing firm and a billion-dollar computing exit are hard to compare on the same scale. We reviewed dozens of UK quantum companies before settling on these fifteen, and two of the entries, Quantinuum and Oxford Ionics, are now foreign owned, which we have flagged clearly rather than pretend otherwise.
Private-company data changes quickly and is often held back from public view, so the figures here are best read as a snapshot in mid-2026 rather than a live ledger. If you run one of these companies and want a detail updated, you can reach us at info@quantumzeitgeist.com. You can also browse our wider directory of quantum computing companies for the global picture.
Frequently Asked Questions
How big is the UK quantum sector? The United Kingdom hosts one of the largest concentrations of quantum companies outside the United States, spread across Oxford, Cambridge, Bristol, London, Glasgow and Birmingham. Government support runs through a National Quantum Strategy worth 2.5 billion pounds over ten years from 2024.
Which is the biggest UK quantum company? By valuation it is Quantinuum, whose April 2026 raise implied a 10 billion dollar figure, although Honeywell holds the majority stake. Among independent British firms, Oxford Quantum Circuits set the funding record with its 260 million pound round in June 2026.
What do these UK quantum companies actually build? They divide roughly into three camps: computing firms building the machines and their software, security firms protecting data against future quantum attacks, and sensing firms using quantum effects to measure gravity, magnetism or gases. This list includes leaders in all three.