Coherence Quantum has closed a €2.78M seed round to build the hardware that carries signals to the qubits inside a quantum computer’s deep-freeze chamber. Lifeline Ventures, an early-stage investor in Helsinki, led the round for the startup, which is based in neighbouring Espoo, Finland.
Mårten Mickos, the technology entrepreneur best known as the former chief executive of the database company MySQL, also invested. In its funding announcement, the company says the money will pay for its own lab in Espoo, first product prototypes, a manufacturing process, further research and a larger team.
Coherence Quantum grew out of the Quantum Computing and Devices group at Aalto University. Its focus is the crowded space around the chip, where wiring and filters have to carry signals in without letting heat and noise reach the qubits.
“Quantum computers won’t scale by adding qubits alone. The infrastructure around them has to scale too,” said Aashish Sah, its co-founder and chief executive.
Wiring Limits Quantum Computers
A qubit is the basic unit of a quantum computer. An ordinary bit is either 0 or 1, but a qubit can hold a blend of both, and that is where quantum machines get their promise for problems such as simulating molecules. The catch is that qubits are extremely fragile.
The superconducting qubits Coherence Quantum works with sit inside a dilution refrigerator, a multi-stage cooler that chills the chip to around 10 millikelvin, a hundredth of a degree above absolute zero. A stray bit of heat or electrical noise can knock a qubit out of its quantum state and spoil the calculation.
Those errors get harder to contain as machines grow, and useful ones will need far more qubits than today’s. Error-correction schemes push the count higher still by grouping many physical qubits into one more reliable unit. Each qubit also needs its own lines to send control pulses in and read results out, and every line runs from warm electronics outside the fridge down to the chip.
Sah says going from hundreds of qubits to 1,000 would take at least 3,000 control lines, while a standard fridge has room for about 1,000. He adds that heat and noise leaking down the wires often make qubits behave as if they sit at 50 to 70 millikelvin, well above the fridge’s own temperature.
Filters That Sit Next To The Qubit
Signals sent from room temperature have to be weakened on the way down so they don’t carry thermal noise with them. Sah says more than 99% of a control signal’s power ends up spent inside the fridge. His argument is about where that happens:
“If it doesn’t dissipate close to the qubit, it doesn’t create noise to the processor.”
The company’s answer starts with signal conditioning, the filters and attenuators that clean up each line before it reaches the qubit. Its website sets out a four-step plan. Protect, available today, guards the qubit environment. Integrate, in development, carries more signals through the cold system. Control, a future direction, would bring more control inside the fridge, and Blueprint is the long-term aim of one combined design.
Sah, Suman Kundu and Mikko Möttönen described the science behind the first step in a 2024 paper in Communications Physics, written with two colleagues. Their on-chip filters block signals at the qubit’s own frequency yet still let it be driven at a fraction of that frequency. With the qubit inside the blocked band, they measured up to a 200-fold rise in how long it held its state.
Coherence Quantum says it has spent more than two years designing and testing several generations of cryogenic prototypes, checked in dilution refrigerators with real qubit systems. It has four patent applications, and Sah says the components covered by the first one cut heat-related disturbance to the qubit by a factor of 100.
Its hardware is aimed at superconducting qubits and at spin qubits, which store information in the spin of single electrons held in semiconductor chips. Both kinds run in deep cold and need many control lines. The company has not named any customers.
A Lab Team Turned Startup
Sah is a quantum physicist who works on superconducting qubits and the electromagnetic surroundings that disturb them, and the filter work began during his doctorate in Möttönen’s lab at Aalto. Kundu, the chief technology officer, is an experimental physicist whose doctorate covered superconducting circuits and cryogenic measurement. The company says he helped set up Aalto’s 20-qubit quantum computer.
Erkki Soininen, the chief product officer, is a physicist with more than 30 years in business leadership, including a product leadership role at Bluefors, the Helsinki maker of dilution refrigerators. He first joined as an adviser while the work was still a university project, before the company spun out.
That project, called ProSQu, ran under Research to Business, a Business Finland programme that funds university teams preparing research for commercial use. Aalto’s innovation portfolio lists ProSQu as a Research to Business project developing filters and attenuators that limit heat during qubit control, and Aalto’s startup centre has named Sah and Kundu as its team.
Backers And An IQM Co-Founder
Möttönen, the founding adviser, is an Academy Professor at Aalto who leads the Quantum Computing and Devices group, and co-founded IQM, the Espoo company that builds full superconducting quantum computers. Coherence Quantum sits further down the supply chain, making parts for machines like those.
Petteri Koponen, founding partner at Lifeline Ventures, framed the deal in the same terms. “If quantum computers are going to scale, the architecture around the qubits has to scale with them,” he said. Mickos called the team impressive and said: “This type of sophisticated technology is needed to turn quantum computing into practical and scalable systems.”
Coherence Quantum now moves from a university lab to a lab of its own in Espoo, with seed money from Lifeline Ventures and Mickos. Its first product line shields qubits from the heat and noise coming down their wires. Its later steps, denser signal interfaces and control moved inside the fridge, are still in development or further out.
For now the performance claims are the company’s own, though its founders’ published research backs part of them. Its bet is that quantum computers will only grow if the hardware around the qubits grows with them.
