Paris-based quantum computing startup C12 has raised an €18m equity funding round to continue developing the technology behind its quantum processors and to develop more commercial partnerships with industrial customers.
It brings the company’s total funding to nearly €30m after it raised a €9m seed round in 2021.
The investment was led by French VC Varsity Capital, UK firm Verve Ventures and the EIC Fund. It also included participation from previous investors 360 Capital, Bpifrance and BNP Paribas, all based in France.
C12 designs and manufactures quantum processors, intending to eventually use the devices to build large-scale quantum computers.
Although still in their infancy, quantum computers are expected by scientists to eventually unlock unprecedented computational power, resolving problems that were previously impossible to process for conventional computers — meaning potentially huge gains for businesses.
What does C12 do?
Across Europe, many startups are working towards building a fully-fledged quantum computer. Just in France, C12 is facing competition from better-funded companies like Pasqal, Quandela and Alice&Bob.
There are different ways to approach the challenge, typically by using different types of qubits — the small particles inside quantum processors that are the equivalent of a bit in classical computers, and which carry quantum information. Pasqal’s approach, called neutral atoms, employs specialised lasers to trap single atoms to form qubits; while Quandela’s qubits are made of particles of light (photons), and Alice&Bob’s of electrons.
C12 uses spin qubits: the startup creates qubits from the spinning movement of electrons trapped on a conventional semiconductor device. Other companies using spin qubits include London-based Quantum Motion and France’s Quobly.
C12 says it differentiates itself by the technology it has developed to host the qubit within the semiconductor.
“In many competing approaches, qubits are insufficiently protected from their environment — meaning they face disturbances that disrupt the quantum nature of the qubit and create errors,” says C12 cofounder Pierre Desjardins.
“These disturbances come from flaws in the material [that hosts the qubit] — often, in the case of spin qubits, silicon.”
The startup creates carbon nanotubes, a material with a high degree of chemical purity made of a single layer of carbon atoms, in which qubits are trapped and then placed on the semiconductor. Desjardins says that this comes close to recreating a vacuum, and ensures that qubits are protected against outside noise.
If demonstrated at scale, this could be a big advantage — given that qubits’ high instability and frequent errors are one of the key challenges holding back the development of large-scale quantum computers.
Producing quantum processors
At the end of 2023, C12 opened a 1k-square-metre underground ‘quantum fab’ in Paris to start producing quantum processors.
This is where the startup manufactures conventional semiconductors and ‘grows’ carbon nanotubes — a process in which a single carbon layer is fabricated by depositing, one after the other, each individual carbon atom. “Our head of growth doesn’t have exactly the same role here as in other startups,” says Desjardins.
The components are then assembled by micro-robots in a vacuum chamber.
“It’s the equivalent of placing a hair on a surface the size of Paris,” says Desjardins.
C12 is producing one processor a week, each carrying one to two qubits.
It doesn’t seem much compared to the 200-qubit computer that Pasqal produces, but Desjardins isn’t worried.
“We’re convinced that we need much better qubits, so for now we are working on our fundamental technology,” he says.
The founder adds that since spin qubits are trapped on conventional semiconductors, the infrastructure is already in place to scale rapidly, contrary to other approaches.
In practice, it is not yet clear that semiconductor manufacturers will be able to seamlessly integrate the production of quantum processors into their existing processes.
There have recently been encouraging indicators, however, with Australian spin qubit startup Diraq announcing last week that it has signed a manufacturing partnership with US semiconductor producer GlobalFoundries.
Desjardins says that C12's manufacturing process, in which quantum components — the carbon nanotubes — are added at the last stage of semiconductor fabrication, is more likely to be compatible with chip makers' existing production lines.
What will the funds be used for?
Desjardins says that the latest injection of cash will largely fund the acceleration of R&D to improve C12’s quantum processors.
Specifically, the goal is to achieve a new technological development related to entanglement — a phenomenon that underpins quantum computing, in which two qubits become connected and share a single quantum state, even if they are at a distance from one another.
C12 says that currently, with other quantum computing approaches, qubits can only become entangled with the qubit that it is nearest to physically. The company is working on enabling entanglement between two distant qubits, within a single chip.
Desjardins says that this allows for better connectivity between qubits — meaning that fewer qubits will be necessary to run computations.
“Without this approach, we think it is impossible to scale quantum computers,” says Desjardins.
“The objective of this fundraise is to achieve, for the first time, this quantum operation between two distant qubits.”
Growing the business
C12 will also focus on securing more partnerships with industrial customers who are interested in exploring ways to apply quantum technology to use cases within their business.
This is a strategy being adopted by other quantum computing startups: Pasqal has partnered with pharmaceutical company Johnson & Johnson and French bank Crédit Agricole, while Quandela works with energy company EDF.
Desjardins says that C12 is already working with a few selected partners in France in the energy and chemistry sectors, such as French industrial gas supplier Air Liquide, and that it hopes to further expand its customer base.
With the technology in such early stages, it is still an exploratory stage for these customers. Desjardins says that with C12’s one and two-qubit chips, it is impossible to test any real-life use case; at least 50-100 qubits will be necessary to start doing so.
As a result, the startup’s main source of revenue, for now, is the support it provides to partners to develop quantum applications, as well as access to a 13-qubit quantum computer simulator.
Desjardins says that commercialisation will accelerate as C12 makes its quantum processors available on the cloud at the end of 2025, and starts selling its first chips in 2026.
