• The UK’s Nu Quantum has raised $60m, the largest financing round for a ‘pure play’ quantum networking company 
• The money will be used to help achieve fault tolerance, the biggest challenge in quantum computing
• The company plans to interconnect quantum processors into a more powerful, distributed and thus much larger quantum computer

Cambridge, UK-based Nu Quantum, which describes itself as “the category creator and leader in distributed quantum computing”, has raised $60m in a Series A funding round in what the company claims is the largest financing round ever by a “pure-play” quantum networking company. 

Nu Quantum was spun out of the University of Cambridge in 2018 with the remit to commercialise research generated and originated by the Cavendish Laboratory, part of the university’s Department of Physics. (The laboratory has been a locus of global excellence in physics since 1874.)

The money raised will be used to bolster Nu Quantum’s stated mission – to achieve fault tolerance by interconnecting quantum processors into a more powerful distributed quantum computer. If Nu Quantum can do it, the company claims it will unlock “the projected $1tn quantum computing market”. 

Quantum computers have the potential to almost instantaneously solve problems way beyond the ability of any supercomputer built on classic computing architecture. To date, the quantum computing industry has focused mainly on improving the power and performance of individual quantum processors. That, in itself, is work of great  value but to achieve quantum technology with real commercial potential and with sufficient dynamic fault tolerance to enable robust and sustainable quantum computing, systems will have to be scalable and able to draw on the incipient power of many thousands more qubits (quantum bits) than presently exist.

Nu Quantum says its quantum networking stack “opens a new approach by enabling quantum computers to scale by weaving individual processors into a modular, distributed computing fabric”. 

While recognising that networking plays a massive role in classical computing and in connecting datacentres and AI infrastructure, the company believes the mass commercialisation of quantum computing will eventually be realised via distributed architectures in quantum datacentres, that will sit on a foundation of Nu Quantum’s networking infrastructure, which rejoices in the title Entanglement Fabric (an excellent name). 

An ‘entanglement fabric’ is a quantum networking architecture, pioneered by Nu Quantum, designed to connect multiple smaller quantum processing units (QPUs), and weaving high-fidelity quantum entanglement between them to create a single, larger, more powerful fault-tolerant quantum computer. In essence, it acts as a quantum internet backbone, enabling modular scaling by addressing the challenge of building beyond single-chip quantum limits and enabling complex quantum error correction. 

The key aspects here are: Modular scaling, which enables the connection of individual quantum processors to overcome physical limitations, allowing for datacentre-scale quantum computing; photonic networking, which employs the basic units of light (photons) to establish entanglement links between distant qubits in different processors; the abstraction layer, which provides a flexible, qubit-agnostic architecture, not-dissimilar to cloud computing, to simplify development and integration; and improved fault tolerance, which enables the complex entanglement patterns necessary for quantum error correction, a key step towards reliable quantum computers.

In essence, it’s the foundational ‘wiring’ and architecture that turns many small quantum computers into one big, powerful quantum supercomputer, making real-world quantum applications feasible. 

Crucially, Nu Quantum’s architecture is adaptable and thus able to support scaling for multiple different qubit modalities. A qubit modality refers to the specific physical system or technology used to create and control qubits in a quantum computer, including trapped ions, photons, superconducting circuits, or neutral atoms (and so on), each of which offers different strengths and challenges in terms of performance, scalability and error rates. The company notes: “Essentially, it’s the ‘how’ of building a qubit, just as a transistor is the ‘how’ for a classical bit, with each modality leveraging different quantum properties.”

Nu Quantum founder and CEO, Dr. Carmen Palacios-Berraquero, commented: “When we launched seven years ago, very few were thinking about networked or distributed quantum computing as a strategy for scaling, but we saw it as one of the most urgent and challenging outstanding problems in the industry, and set out to solve it. We’ve made great strides in shaping the market and the technology since then… this investment validates our vision and the maturity of our solution as the path to scaling,” she added.

Nu Quantum’s Series A funding round was led by a new investor, Los Angeles-based National Grid Partners, the corporate venture and innovation arm of National Grid, one of the world’s biggest investor-owned energy companies. Steve Smith, chief strategy and regulation officer of National Grid and president of National Grid Partners, stated: “We are closer to quantum computing having an impact on businesses and lives than many people think. Nu Quantum is at the forefront of bringing this powerful technology closer to market and using it to solve real-world challenges today.” 

Other participants in the funding round included Gresham House Ventures and Morpheus Ventures, whilst existing investors are Ahren Capital, Amadeus Capital Partners, Cambridge Enterprise Ventures, East Innovate, IQ Capital, NSSIF, and Sumitomo (Presidio Ventures).

Quantum computing networking and entanglement fabric

Looking to the future, Nu Quantum, which earlier this year helped to launch the Quantum Data Centre Alliance with the likes of Cisco and NTT Data, plans to use the money it has raised to build on the “success” of its “world-first quantum networking subsystems”, the Qubit-Photon Interface, unveiled in 2024, and the Quantum Networking Unit, which was announced earlier this year. The overall system architecture will be informed by [the company’s] pioneering work on distributed quantum error correction,” it noted.

The funding will also support Nu Quantum’s international expansion, including the growth of its presence across Europe and the US: The company opened an office in Los Angeles, California last year.

Quantum computers rely on qubits and robust high-quality entanglement between them to run immensely powerful computations. Moving beyond isolated, individual  processors will require the creation of entanglement links between qubits in adjacent processors, via the medium of photonic quantum networking. Achieving this with high fidelity is the key technical challenge now facing those scientists attempting to develop the modular scaling of quantum computers, communications and sensor networks. 

The quantum networking layer sits atop the physical networking layer and below the transport and application layers in the quantum network stack model. It is an emergent quantum network architecture and is primarily responsible for end-to-end entanglement distribution across a network of connected quantum devices. Its main function is to enable the transmission of quantum information between non-neighbouring nodes by using techniques such as entanglement swapping and routing protocols. 

It is inspired by the original internet’s network layer, which uses IP addresses for routing data packets. However, the quantum networking layer manages how quantum information, specifically entangled qubit pairs, travels across intermediate quantum repeaters or routers to reach its final destination. To that end, ‘entanglement routing’ chooses the most appropriate path within the network to establish an end-to-end entanglement link between two desired end nodes. 

Meanwhile, ‘entanglement swapping’ uses measurements taken at intermediate nodes to “swap" entanglement, thus extending a shared entangled pair from two short links into one longer link. Then, ‘addressing and node discovery’ manages the logical addresses of quantum nodes (Q-nodes) and selects intermediate nodes (quantum repeaters) to provide long-distance communication.

The development of a functional and interoperable quantum networking layer is a huge challenge, with research groups and companies such as Nu Quantum and the Quantum Internet Alliance working to create the necessary software and hardware for future quantum networks. 

– Martyn Warwick, Editor in Chief, TelecomTV