PsiQuantum wants to build a quantum computer that looks like a data center crossed with an ice cream factory: 100 stainless-steel cabinets, each cooled by liquid helium to a few degrees above absolute zero, with thousands of photons zipping through optical switches and beam splitters. The goal? Solving problems that would take today's computers millions of years. The catch? The machine doesn't exist yet.

The company, founded in 2016 by four UK physicists, aims to be the first to deliver a useful quantum computer. Unlike Google and IBM, which bet on superconducting qubits, PsiQuantum is using photons - particles of light. Photons maintain quantum states for a long time (the cosmic microwave background has had billions of years to prove that), but they're terrible at interacting with each other. A 2001 paper found a loophole using beam splitters and detectors, and PsiQuantum has been chasing that dream ever since.

PsiQuantum has raised $1 billion, broken ground on a site in Chicago, and promises a second site in Australia will be operational by 2027. It's one of two companies (along with Microsoft) to reach the third stage of a government evaluation program. But verifying quantum computing progress is harder than judging a drug trial - everything is incremental, opaque, and tough to verify from the outside. The company's prove-it moment is coming, possibly as soon as next year.

Co-founder Terry Rudolph, grandson of Erwin Schrödinger (yes, that Schrödinger), wrote a 150-page book explaining quantum computing to teenagers. He and his co-founders believe the technology could revolutionize drug design, battery safety, and materials science. But first they need to manufacture barium titanate crystals in-house, cool their detectors to -456 °F, and ensure photons don't scatter before finishing their calculations. No pressure.