Google hit 105 qubits with Willow. IBM says 100,000 by 2033. Quantinuum has 98 with the best error-correction numbers in the industry. Every press release is a qubit count. Every milestone is a number going up.
Nobody talks about the cables.
Every qubit in a quantum computer needs coaxial cables running from the processor, which sits inside a dilution refrigerator at temperatures near absolute zero (roughly 4 Kelvin, or minus 269 Celsius), up to room-temperature control electronics. These are physical wires. They carry microwave signals. They generate heat. And there are a lot of them.
IBM’s 1,121-qubit Condor chip, announced in late 2023, required a cryogenic system packed with wiring that already pushed the limits of what a dilution refrigerator could physically contain. IBM’s public roadmap calls for 100,000 qubits by 2033. There is no corresponding public roadmap for how to wire 100,000 qubits.
That silence is worth paying attention to.
The quantum industry has a habit of measuring progress in qubit counts and error rates. Those metrics matter. They are also useless if you cannot physically wire the machine. A 100,000-qubit computer connected by 100,000 coaxial cables is an engineering fantasy. The cables do not shrink. The fridge does not grow. Something has to replace the wiring, and the companies building the qubits either haven’t solved it or aren’t saying how they plan to.
This is the gap that companies like Rhonexum are trying to fill.
$1M, Two Founders, One Bet
Rhonexum, an EPFL spinout based in Lausanne, Switzerland, raised $1 million in pre-seed funding on March 18. The round was led by QDNL Participations, a specialist early-stage quantum VC firm, with additional support from the Swiss National Science Foundation, Venture Kick, and Fondation pour l’Innovation Technologique.
The company was founded in November 2025 by Vicente Carbon and Dr. Hung-Chi Han. Carbon has a background in robotics and systems engineering. Dr. Han is a published researcher in cryogenic semiconductor physics who previously worked on cryogenic transistor modeling at TSMC, the world’s largest chip manufacturer. They spun out of EPFL’s AQUA Lab, which focuses on analog and quantum computing.
Their thesis: replace the cables with chips. Specifically, cryo-CMOS integrated circuits that operate at temperatures near absolute zero, sitting right next to the quantum processor inside the fridge. Instead of running thousands of coaxial cables up to room-temperature electronics, you put the control electronics on a chip that works in the cold. Fewer cables. Less heat leaking into the system. More room to scale.
Why CMOS Matters
The word “cryogenic” makes this sound exotic. It is not. Or at least, that is what Rhonexum is betting on.
Standard CMOS (complementary metal-oxide semiconductor) is the manufacturing process behind almost every chip on the planet. Your phone, your laptop, the servers running this website. The catch: CMOS transistors behave differently at cryogenic temperatures. The physics changes. Threshold voltages shift. Carrier mobility behaves in ways that room-temperature models do not predict. You cannot just take a regular chip design, cool it to 4 Kelvin, and expect it to work.
Rhonexum’s edge, according to the Quantum Computing Report, is proprietary modeling software that simulates cryogenic semiconductor physics before fabrication. Dr. Han’s TSMC background is the foundation here. He spent years building models of how transistors behave at extreme cold. That means Rhonexum can design chips, simulate their cryogenic behavior, and iterate without the cost and time of fabricating each prototype. And when they do fabricate, they use standard CMOS foundry processes. No exotic materials. No custom fabrication lines. Just chips made the normal way, designed to work in abnormal conditions.
QDNL’s investment director Kris Kaczmarek called the software-driven approach a key differentiator, noting it allows “faster and more cost-effective hardware development.”
The company plans to deliver its first industrial-grade cryogenic product to early customers by late 2026.
The Honest Assessment
Laterstack covering a $1M pre-seed is unusual. A million dollars is small. This is a two-person EPFL spinout with proprietary simulation software and a theoretical framework, not a proven product in a customer’s fridge. There are other teams working on cryo-CMOS. Intel has explored cryogenic control chips. Startups like Equal1 have been pursuing on-chip qubit control for years. Rhonexum is not alone in seeing the problem.
But the problem itself is what deserves coverage. Not the company.
The entire quantum computing roadmap, from every major player, assumes a wiring solution will exist when the qubit counts demand it. IBM does not publish a cable roadmap alongside its qubit roadmap. Google does not discuss it in its Willow announcements. The industry treats the connection layer like someone else’s problem. And maybe it is. Maybe IBM and Google have internal solutions they haven’t disclosed. That would be rational. But the public conversation acts as if scaling qubits is the hard part and everything else will follow. History suggests that the boring infrastructure problem is usually the one that kills you.
Whether Rhonexum specifically is the company that solves this is an open question. Whether someone needs to is not.
Co-founder Carbon framed the ambition clearly: “We founded Rhonexum to become the key provider of cryogenic electronics for scalable quantum computers,” he told The Quantum Insider. The company also sees applications beyond quantum, in space systems and advanced sensing, anywhere electronics need to work in extreme cold.
The qubit press releases keep coming. The cables are not going anywhere on their own.
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