Forbes France offers you a report in the depths of the C12 underground laboratory, in the heart of Paris. The startup, which has just raised 18 million euros, wants to create the first carbon nanotube quantum computer using a new generation factory.
To unravel the mysteries of quantum computing, C12 has designed a real underground factory for the production of nanoelectronic components. With a particularity which constitutes the trademark of the startup: the design of carbon nanotubes to create stable qubits, an essential variable for the birth of the first quantum computer. Reporting.
High degree of technicality
The meeting is set for October 29 in the 5th arrondissement of Paris, not far from the Panthéon and a stone’s throw from Place de l’Estrapade – one of the filming locations for Emily in Paris which attracts a constant flow of fans of the series. On the ground floor there is an open space, which could not be more ordinary. “C12 is hiring 45 people from 18 nationalities”, it is explained in the introduction to highlight a wide variety of internal profiles, whose expertise is highly sought after.
You only need to walk a few meters to realize the level of technical skills you will need to equip yourself with to avoid getting lost. At the back of the room is a strange 2 meter cylinder, suspended upside down, behind a glass wall. This is the heart of the future C12 quantum computer, which maintains an electronic chip at a temperature of around -273°C – close to absolute zero – and which isolates it from all external disturbances.
A sort of cocoon connected by a jungle of cables to numerous boxes and machines in continuous operation. The installation, which would make any computer neophyte pale, serves as a warning: C12 is not a simple digital startup and presents an ambitious R&D project that requires millimeter precision.
Or rather to the nanometer. Because it is in the infinitely small that the quantum computing revolution is taking place. And faced with its French competitors like Pasqal, Quandela and Alice & Bob, C12 made a daring bet: the latter wants to replace the silicon in processors with carbon, known to be more stable for producing the precious qubits. “Carbon 12 helps prevent the nuclear spin of atoms,” adds Pierre Desjardins. “It is an extremely pure material, which protects and isolates an electron from its environment.”
From classical bit to quantum qubit
At this point, we’ve probably lost more than one. So let’s try to describe the process of creating a qubit as simply as possible. The classic bit in computing is a unit of measurement designating the elementary quantity of information represented by a binary digit, and which can therefore only take two values: 0 or 1.
To explore the subject, see this video:
For its part, the quantum bit or qubit is the elementary unit that can carry quantum information. And just like classical bits, qubits rely on two basic states which are state zero |0> and state one |1>. To obtain a qubit, C12 must therefore ensure that each of its nanotubes contains a single trapped electron, whose spin is manipulated to become a state of the qubit. The spin here represents a characteristic of a quantum particle, in the same way as its mass or its electric charge, and a quantum processor cannot function without it.
This quantum trapping is the key to the proper functioning of C12 processors and it depends greatly on the quality of the carbon nanotubes produced upstream. This process, born from a spin-off from the Physics Laboratory of the Ecole Normale Supérieure de Paris and developed in partnership with the CEA, is still imperfect. But it achieves error rates low enough to already solve certain industrial problems. The technology is, for example, particularly interesting for simulating chemical reactions and is already of interest to large groups such as Air Liquide.
The phenomena here are explained using the laws of quantum physics and it turns out that the quantum computer calculates using these same laws. But it can also solve complex combinatorial problems much more quickly, particularly in terms of logistics optimization.
In the depths of the nanotube factory
Now let’s leave the offices to go to the laboratory one floor down. Because it is in the basement that the most precious secrets of C12 are buried and this is not a choice made at random. An underground space is firstly easier to keep cool, an essential element for this type of production. But it’s also about being isolated as much as possible from the outside world.
“High floors tend to move or be sensitive to vibrations,” explains Pierre Desjardins, which can have an impact on the stability of quantum calculations. So, when C12 visited the premises, a team of experts was tasked with carrying out a battery of tests to measure potential vibrations, the presence of electromagnetic fields and all types of interference capable of becoming disturbances.
So many parameters which convinced the startup to set their sights on these premises located at the top of the Sainte-Geneviève mountain. “There is no metro under the foundations either,” adds Pierre Desjardins. Finally, the lessor of the premises chose C12 from 2022 as the new tenant. The latter also had in hand a competing file from a certain Jean-Claude Van Damme, also looking for a place to open a new sports club.
On floor -1, we first enter a clean, sanitized room littered with test tubes and instruments of all kinds. But also again machines, even more imposing, which make it possible, among other things, to carry out the first step: manufacturing electronic chips and printed circuits from scratch in order to be able to deposit the famous carbon nanotubes.
The second room contains unpatented technology kept secret at all costs. The process is innovative and meticulous: it consists of forging a carbon nanotube with a wall made up of a single layer of atom. Ultimately, C12 will only keep the most promising candidates, in other words between 5 and 20% of them. A very selective and constantly evolving characterization process. For example, this involves projecting a laser through the nanotubes to reveal the existence of defects.
“Roughly speaking, the more crystalline the light reflection that emerges, the purer the composition,” explains Alice Castan, researcher and head of the characterization team, who is imagining other types of tests to be deployed in the near future. The growth of 300 nanotubes in the laboratory takes around thirty minutes while the technical control lasts a few days.
“1000 times smaller than a hair”
The last step involves assembling the nanotubes on the printed circuits, an operation also protected by patent and above all isolated from any potential contamination. A simple grain of dust can ruin handling. “The diameter of a nanotube is 1000 times smaller than a hair,” insists Pierre Desjardins. Thus, the machine equipped with robotic arms on a microscopic scale places the nanotubes on a chip, which is equivalent to placing a hair on a street on the scale of the city of Paris.
Forbes France was exclusively able to enter this highly protected assembly room. In the center is a sort of steel box equipped with portholes so that the assembly can be observed under a microscope. “Our biggest enemy remains the contact of the nanotube with the printed circuit,” explains Davide Stefani, researcher and head of the nano-assembly team.
It is now time to resurface and the end of this visit concludes with a presentation of future projects for the tricolor nugget of quantum. “We have successfully demonstrated the material part and the challenge now is to scale up,” projects Pierre Desjardins. The latter is counting in particular on the 18 million euros raised last June in pre-series A to conclude new commercial and industrial partnerships.
The objective is to achieve fairly quickly the entanglement of two qubits, a fairly complex concept which describes the fact that the quantum states of the latter are linked. In other words, a communication bus is created between two qubits located several millimeters apart. This would, for example, solve the puzzle that assembling nanotubes on a chip can represent – precisely because they can now be spaced further apart.
“There are no clearly identified business benefits at the moment,” admits Pierre Desjardins. On the other hand, the quantum computer will have a certain economic impact, so we must prepare now.” For this, C12 recently launched its first product: Callisto, an emulator capable of running algorithms using up to 13 qubits on conventional processors.
But in this restricted universe of quantum research, another race for time is underway and involves big names in tech like Google and IBM. “Our first objective is to integrate the first quantum processor into a classical computer system by the end of 2025,” maintains Pierre Desjardins. This will allow the computer to run hybrid algorithms, mixing both quantum and classical computing. “IBM has just announced a similar roadmap and our ambition is to succeed before them in ensuring that qubits can be placed anywhere on a quantum chip,” he promises.
To stand up to the giants of the sector, C12 was also selected for the Proqcima program launched in March 2024 by the Ministry of the Armed Forces in collaboration with the General Secretariat for Investment (SGPI). It aims to have two prototypes of French-designed universal quantum computers by 2032.
Also read: Pierre Desjardins, CEO and co-founder of C12: “As with AI, quantum will cause a major technological breakthrough”
