PsiQuantum lays out its bet on a million-qubit computer built from light
PsiQuantum, founded in 2016 by four physicists, is taking a different route to quantum computing than most of its rivals: rather than superconducting circuits or trapped ions, it encodes qubits in individual photons and processes them on silicon photonic chips manufactured with conventional chipmaking techniques. The company’s argument is that using standard semiconductor fabs is the only path to the sheer number of components a useful machine will need.
The target is roughly a million qubits — the scale generally thought necessary for error-corrected, or fault-tolerant, computing that could tackle real problems in drug discovery, materials science and cryptography. PsiQuantum says it is now operating three connected cabinets holding 250 chips each at its Milpitas, California site, has raised about $1 billion, secured $100 million in CHIPS Act funding for photon detectors, and broken ground on facilities in Chicago and Australia, with the Australian site slated to be operational by the end of 2027. It is one of two companies, alongside Microsoft, to reach the third stage of DARPA’s quantum benchmarking program.
The caveats are real. “Operational” here means the supporting cooling and infrastructure are ready, not that a full million-qubit machine exists, and researchers note that improvements remain modest until very large systems are built. The photonic approach still has to prove it can hit that scale — but the plan clarifies how at least one well-funded contender intends to get there.