PsiQuantum

PsiQuantum is one of the most heavily funded quantum computing companies in the world. Its home address is a quiet street in Palo Alto. The company wants to build a quantum computer large enough to correct its own errors and run useful programs. Its bet is unusual. Instead of trapped ions or supercooled circuits, it uses single particles of light. It also makes its chips in an ordinary commercial semiconductor plant.

This profile covers what PsiQuantum does, where it came from, what it has announced so far and how it fits into Palo Alto. Like most of the companies in our Palo Alto companies guide, it has no public face here. You can see the street, not the lab.

What PsiQuantum is building

A quantum computer stores information in qubits, which can hold a blend of zero and one at the same time. In theory a large enough machine could solve some chemistry, materials and optimization problems that ordinary computers cannot touch. In practice qubits are fragile. They lose their information quickly, so useful machines need error correction, which takes many physical qubits to make each reliable logical one.

PsiQuantum's answer is photonics. Its qubits are photons that travel through waveguides etched into silicon chips. Light does not need to be held near absolute zero the way some qubit types do, although the company's detectors still need deep cooling. The bigger argument is manufacturing. Silicon photonics already runs through data centers, so the company says it can borrow the tools and factories of the chip industry rather than invent new ones.

Fusion-based quantum computing

In early 2021 PsiQuantum researchers described an architecture called fusion-based quantum computing. It builds a large computation out of small entangled clusters of photons that are joined, or fused, by measurements. The paper later appeared in Nature Communications in 2023. The company describes the design as a key part of its route to a fault tolerant machine.

Founding in 2016

PsiQuantum was founded in 2016 by four physicists: Jeremy O'Brien, Terry Rudolph, Peter Shadbolt and Mark Thompson. They had worked as professors or researchers at the University of Bristol and Imperial College London in England, two centers of photonic quantum research. O'Brien serves as chief executive.

The founders chose to set up in Palo Alto rather than near their old universities. The reasons are familiar ones for a hardware company with very large capital needs. The Peninsula has deep venture funds, chip industry veterans and a long history of companies that turned laboratory physics into products. One of the company's early backers, Playground Global, is a deep tech fund based on Portage Avenue in Palo Alto. Its portfolio page lists PsiQuantum among its best known bets.

Milestones so far

PsiQuantum has not yet shown a working fault tolerant computer. Its public record is a series of manufacturing steps, government contracts and site announcements.

Products and research tools

Most of what PsiQuantum makes is still inside its labs. Two names show up in its public announcements.

• Omega. A silicon photonics chipset announced in 2025. The company says it gathers the optical parts needed for large scale quantum computing onto chips that can be made in volume.
• Construct. A software suite for designing fault tolerant quantum algorithms. PsiQuantum launched it in 2025 and in 2026 made it available to all developers at no charge.

The company also works with Nvidia. When it announced its 2025 funding round, it said the two would collaborate on quantum algorithms, on linking GPUs with quantum processors and on its photonics platform.

Funding and investors

PsiQuantum is privately held and has raised money in large rounds. On September 10, 2025 it announced a $1 billion Series E that valued the company at $7 billion. Funds managed by BlackRock affiliates, Temasek and Baillie Gifford led the round. New investors included Macquarie Capital, Ribbit Capital, Nvidia's venture arm NVentures and the Qatar Investment Authority. Blackbird, Third Point Ventures and T. Rowe Price were among existing backers that joined again.

Government support is a large part of the story too. The Australian package, the Chicago park and the proposed CHIPS incentives all tie public money to the construction of specific machines. Quantum hardware is a long game. The company says its funding will go toward building those sites.

PsiQuantum and Palo Alto

The company's contact page gives a mailing address of 700 Hansen Way, Palo Alto. Hansen Way is a short street in Stanford Research Park, near where Page Mill Road meets El Camino Real. It has a long hardware history. Varian's medical business still lists 3100 Hansen Way. The microwave tube maker Communications and Power Industries used 811 Hansen Way in a 2004 filing. Nest was based at 900 Hansen Way in early 2014.

That makes PsiQuantum part of a long line of physics companies on this street. Klystrons born in a Stanford basement were built here for decades. Our Varian profile tells that story.

Stanford ties

We found no formal research partnership between PsiQuantum and Stanford in the company's own announcements. The link is geographic. The research park sits on land Stanford leases to companies. Stanford's physics, electrical engineering and applied physics departments train many of the people who work in photonics and quantum hardware. Job seekers will find that the company's postings list Palo Alto along with its other sites.

PsiQuantum's work is spread across several places. Chips come from New York. Large machines are planned for Queensland and Chicago. Cryogenic research runs in England. Palo Alto is the corporate address and a base for engineering, but it is not where the first big computers will stand.

Visiting and nearby

There is nothing to tour. The Hansen Way building is a private office with badge access and no visitor center. Do not walk into the lobby or parking areas without an appointment. You can see the street from Page Mill Road, but there is no sign or marker worth a special trip.

Getting there and food

The nearest Caltrain stop is California Avenue, roughly a mile away on foot or bike. Caltrain runs from there to San Francisco and San Jose. Express trains stop at the main Palo Alto station instead. VTA buses run along El Camino Real. Many research park employees bike in.

For lunch, the car-free blocks of California Avenue are close. La Bodeguita del Medio serves Cuban food and Terún serves Neapolitan pizza. Coupa Café runs the coffee shop at The Hub, the research park's gathering space at 3215 Porter Drive. Along El Camino Real near Hansen Way, Yutori serves Japanese food.

What to watch

PsiQuantum has set out an ambitious timeline. When it raised its Series E, the Wall Street Journal reported the company saying its computer would be ready in two years. Outside experts have long debated how fast any approach can reach useful scale. Photonics has its own hurdles, including losing photons along the way. The next public signs to watch are progress at the Brisbane and Chicago sites and results from the DARPA evaluation.

For the wider picture of deep tech in Palo Alto, from klystrons to quantum chips, see our Silicon Valley history.

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