g2-Zero: Making Quantum Light Practical, Plug-and-Play, and Ready to Scale

g2-Zero, a deep-tech company based in Madrid, Spain, is tackling one of the hardest bottlenecks in quantum technology: the reliable supply of single photons. As a member of the PhotonHub Scaling Club, the company is developing electrically driven single photon sources: a foundational building block for quantum communications, quantum computing, and quantum sensing, that can be manufactured at industrial volume.

Benito Alén, acting CEO and co-founder of g2-Zero, shared the company’s vision: “Our ambition is that, for the first time, the light that quantum technology runs on can be produced in real volume, for anyone who needs it.”

This is not a business idea picked up along the way. Alén is a career physicist and tenured researcher at the Spanish National Research Council (CSIC), and the principal inventor of the technology the company is built on,the result of years of work in the lab before the team set out to bring it into the real world.

A single photon source you can plug in and use

Single photon sources are the foundation of photonic quantum technology, yet they remain notoriously difficult to produce. Every quantum communication network, photonic quantum computer, or sensing system needs a large and steady supply of single particles of light, and today that supply is one of the field’s tightest constraints.

g2-Zero’s answer is a source designed to be, in effect, plug-and-play. “What we’ve built is a single photon source you can essentially plug in and use,” explained Alén. “It runs on electricity alone, without the complications coming from optical driving and alignment, it’s robust, and we designed it to be made in the same semiconductor manufacturing world that already produces the lasers behind data centres and fibre networks.” The device is driven and tuned entirely by electricity, with performance boosted by a tiny optical cavity built directly into it: the aim being a source that is bright, easy to operate, and ready to be made at scale, all at once.

The technology comes out of the Institute of Micro and Nanotechnology of the CSIC, where the team develops its devices in the cleanroom, while also partnering with cleanrooms across Europe. The founders have spent their careers on every part of these devices — the modelling, the fabrication, and the characterisation of semiconductor structures at the nanoscale.

Removing the bottleneck holding quantum back

The scale of what is coming makes the problem urgent. Research suggests a single useful photonic quantum computer could need more than ten thousand of these sources, while global quantum communication networks could require hundreds of thousands of nodes, each with several sources of their own, far beyond what anyone can currently make.

Alén sees a clear historical parallel. “Generating bright, controllable light on demand used to be genuinely difficult. The first lasers were bulky, temperamental, and almost impossible to deploy widely,” he said. “The turning point was electrical injection. Once you could drive a laser with a current, it became practical, manufacturable, and eventually ended up in every home and network on earth. We’re bringing the same change to quantum light.”

That, he adds, is the heart of the company’s edge: “Our secret sauce isn’t a single trick. It’s a patent that took years to develop, a team that understands these devices end to end, and a real roadmap to making them in volume.”

Two priorities: product and scale

g2-Zero is advancing two efforts in parallel. The first is product: consolidating its work into a first working version that can go into real test environments and collaborative research projects, so users can see what high-performance, electrically driven single photon sources can do for them. The second is scale: proving that the devices can run unattended, around the clock, and be produced in industrial volumes rather than one at a time on a lab bench.

“Showing that these devices can be made in volume is the whole game for us,” said Alén. The company is proving out that manufacturing with specialised cleanrooms across Europe, including a technical upscaling project to be run through PhotonHub. A financial plan sits behind both efforts, and g2-Zero is currently raising a seed round, actively seeking investors to join at this stage.

Strong validation from deep-tech and industry programmes

g2-Zero has gathered notable external validation. The company was selected for the first cohort of DIANA, NATO’s deep-tech accelerator, a highly competitive programme whose recognition signalled that a reliable supply of quantum light is seen as strategically important, not just scientifically interesting. It has won competitive public grants and closed a pre-seed round that included the corporate venture arm of photonics giant Hamamatsu.

The team has also been accepted into a series of demanding programmes that bring it closer to industry: the European Space Agency’s Business Incubation Centre, the MadQuantum Business Venture programme tied to the European quantum communications initiative Euro-QCI, and the MIT-affiliated StartSmart programme.

A team that built the technology it sells

g2-Zero’s founders invented the core technology and now lead the company, so there is no gap between the science and the strategy. The scientific founding team brings together some seventy-five years of combined experience in quantum technologies and covers the full lifecycle of these devices: the modelling to design them, the fabrication know-how to build them, and rare characterisation capabilities to prove exactly what they do.

“Our hardware won’t fail in the handoffs of the development cycle, because the people who design the device understand how it’s made,” said Alén. Rooted in a leading research institute and supported by a network of cleanroom partners across Europe, the company can develop and scale without owning every piece of infrastructure itself, staying lean while moving toward real manufacturing.

PhotonHub Scaling Club: widening the network and reaching the right investors

Joining the PhotonHub Scaling Club supports g2-Zero on two fronts. “We’re a quantum photonics company that makes semiconductor devices, so our progress depends on cleanroom partners who can run certain processes for us, and the Scaling Club is how we widen that network,” Alén explained. “It also gives us resilience: if you depend on one or two suppliers for a critical step, you’re exposed the moment something goes wrong.”

The second is funding. “Quantum and photonics are specialised enough that not every investor understands them, so being connected to people who do is a real advantage,” he said. “Through its roadshows and introductions, the Scaling Club puts us in front of cornerstone investors and partners who already grasp what we’re building and why it matters. For our seed round roadshow, that kind of targeted access is worth a great deal.”

Building toward quantum light at scale

Hardware is a key limiting factor in quantum technology today, and quantum light sources are a large part of that challenge. g2-Zero is focused squarely on the hardest piece, producing deployment-ready devices in volume, and is keen to hear from those working on the problem from every side: investors who back deep-tech companies at seed stage, and partners in photonics and semiconductors.

When quantum light stops being scarce and becomes something you can simply order off the shelf, as Alén puts it, people will build things with it that nobody has thought of yet.

Learn more about g2-Zero and its work in single photon sources: https://www.g2-zero.com/.

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