Technology — PsiQuantum

A silicon photonics platform built for the future of computing

PsiQuantum has developed a leading-edge silicon photonics platform that enables utility-scale quantum computing and creates new opportunities for computing to scale.

Built to solve one of the world's hardest engineering challenges, the platform combines advanced photonics, manufacturing, and networking technologies that can be applied beyond quantum computing, including optical networking solutions for next-generation AI infrastructure.

Inside a utility-scale quantum computer

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Wafer

Photonic components, including single photon sources, single-photon detectors, and an ultra-high-performance optical switch, are fabricated in a high-volume semiconductor foundry on standard silicon wafers.

Photonic qubits avoid exotic materials and fabrication processes and are able to leverage the existing reliability, volume, and precision of standard semiconductor manufacturing.

WAFER SIZE 300MM

DEVICES TESTED >1M

LITHOGRAPHY NODE 45NM

Chip

Photonic qubits are implemented by repurposing integrated photonics technology, originally developed for telecom and datacenter networking applications.

Entangled states — specially designed to implement quantum error-correcting codes — are created and measured using fusion gates.

Nondeterministic photon sources and gate operations are made scalable via a combination of multiplexing and loss-tolerant error correcting codes

SINGLE-QUBIT FIDELITY 99.99% ¹

TWO-QUBIT FIDELITY >99% ²

Package

Photonic chips are integrated with cryogenic control electronics into a manufacturable package.

Despite the fact that some of these packages must be operated at cryogenic temperature, we are able to use conventional technologies — PCBs, copper heat sinks and bump bonding. As a result, PsiQuantum can leverage conventional contract manufacturing to build large numbers of packages quickly.

Photonic qubits can be networked and modularized using standard optical fiber, without transduction — a huge advantage at scale.

Blade

Building a utility-scale quantum computer requires installing thousands of photonic packages. We adopt a proven model from classical computing: modular, rack-based infrastructure. Conventional supercomputers are increasingly turning to liquid cooling as density and TDP increases. We cool our chips using liquid helium, which ﬂows through a cryogenically-cooled copper backplane — analogous to the backplane in a conventional server rack.

Our blade is the scalable unit of cryogenic quantum computing racking. It houses many individual photonic-packages networked together with fiber and control signals.

Cabinet

The dilution refrigerator—or ‘chandelier’—has become an iconic image of quantum computing, yet it is severely constrained in both the number of chips it can cool simultaneously and its overall cooling capacity.

Because photons are unaﬀected by heat, our systems can operate at temperatures more than 100 times higher than those required for superconducting qubits. This higher operating temperature enables PsiQuantum to move beyond the chandelier to far simpler, high-density cryogenic cabinets. Each cabinet provides thousands of times the cooling power of the largest dilution refrigerator ever built,³ and can accommodate hundreds of quantum chips.

COOLING POWER PER CABINET ~30W

Quantum Computer

Most architectures for quantum computing will require major physical infrastructure in order to deliver enough qubits for commercially useful applications and to scale far beyond.

In 2024, PsiQuantum announced two landmark partnerships with the Australian Federal and Queensland State governments, as well as the State of Illinois and the City of Chicago, to build its first utility-scale quantum computers in Brisbane and Chicago. Recognizing quantum as a critical capability for the future, these partnerships underscore the urgency toward building and deploying million-qubit systems. In 2025, PsiQuantum broke ground on America's largest quantum computing project at the Illinois Quantum and Microelectronics Park in Chicago––and the company will soon break ground on its facility in Australia.

Omega: the foundation of our photonics platform

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Mass-manufacturable quantum chips

When we think of manufacturing for quantum computing, we typically imagine a small-scale university cleanroom or an R&D fab which can accommodate exotic materials, atomic scale fabrication, and novel devices — and, by extension, a long road to scale.

PsiQuantum's wafers are now built by the thousands, at the highest possible level of technical maturity — in a high-volume, commercial semiconductor foundry. Our Omega platform integrates superconducting single photon detectors, single photon sources, and a high-performance optical switch into a single ultra-low-loss silicon nitride platform, containing all the components we need for optical quantum computing, each having beyond-state-of-the-art performance.

Learn more in our manuscript published in Nature.

Source

PsiQuantum's qubits are encoded using telecom-band (1550nm) single photons, generated on-chip using resonantly-enhanced spontaneous four-wave-mixing.

SOURCE PURITY ~ 99.8%

HOM VISIBILITY, UNTUNED RINGS ~ 99.7%

Interferometer

To perform single-qubit and two-qubit gates, we split and recombine photons using on-chip interferometers.

Thanks to the extreme process control of our manufacturing process, our interferometers achieve up to 99.999% fidelity.

EXTINCTION RATIO > 50dB

Edge Coupler

We're fortunate that we can network chips using standard telecom fiber, but it's important we don't lose qubits at the interface. Chip-to-fiber coupling must be ultra-low-loss.

We’ve reduced industry standard losses from ~50% to ~1%, enabling die-to-die networking at error-correction-compatible levels.

COUPLING LOSS ~ 50mdB

Switch

The biggest obstacle to the scaleup of photonic quantum computing is the fact that the photon sources and gates are both nondeterministic. The key to overcoming this challenge is fast, low-loss optical switching. PsiQuantum built the biggest molecular beam epitaxy tool in the world and successfully delivered a 300mm manufacturing process for optical switches based on Barium Titanate (BTO) — the "holy grail" of optical switching materials.

LOSS ~ 10dB/m

ELECTRO OPTIC COEFFICIENT ~ 1000pm/V

Detector

We use single photons as our quantum information carriers.

Superconducting films, biased near their transition point, enable efficient single-photon detection. We have introduced near-perfect superconducting films into our manufacturing flow, and now manufacture millions of waveguide-integrated photon-number-resolving superconducting single-photon detectors at GlobalFoundries.

We’ve extended this to photon-number resolution, critical for entanglement and error reduction.

ON-CHIP EFFICIENCY ~ 98%

Yielding record-breaking quantum performance metrics

99.98%

± 0.01% single-qubit SPAM fidelity

Confirming near-perfect qubit initialization and readout

99.5%

± 0.25% quantum interference visibility

Proving the indistinguishability of photons from independent sources

99.72%

± 0.04% chip-to-chip fidelity

Demonstrating high-fidelity qubit transmission over optical fiber

99.22%

± 0.12% two-qubit fusion fidelity

Validating the accuracy of our entangling operations

Quantum state tomography of a dual-rail photonic qubit with on-chip single photon sources and superconducting detectors. No multiplexing.
Bell state projection. No multiplexing.
Colossus, ~1mW @ 10mK