PsiQuantum's Plan for a Massive Quantum Computer Using Light

PsiQuantum's machine, if successful, could change the world. Housed in a room resembling a data center and an ice cream factory, it will feature 100 stainless-steel cabinets, each about six feet tall, connected to a supply of liquid helium that keeps them a few degrees above absolute zero. Inside these cabinets, hundreds of chips will contain thousands of particles of light flying through a maze of optical switches and beam splitters.

Each photon must be accounted for, as precisely measuring its path will help answer questions that current computers might take millions of years to solve. PsiQuantum, founded in 2016 by four physicists from UK universities, aims to be the first to fulfill its promise in a crowded field of deep-pocketed competitors with similarly ambitious visions. The company's goals include predicting the effects of cytochrome P450 enzymes, which often break down drugs in the body.

By simulating how these enzymes work on specific molecules, pharma companies could design more effective medications faster. Philipp Ernst, vice president of quantum applications at PsiQuantum, claims they can reduce the estimation time for a specific drug from over 10 years to four minutes. PsiQuantum has attracted significant investment and scrutiny, partly because it's one of the few companies directly aiming to build a large and useful machine.

The company has partnered with a major chip manufacturer to build its systems using existing semiconductor fabs. Last year, PsiQuantum raised $1 billion in funding and broke ground in Chicago on a site being built in partnership with local governments. Another site is being developed in Australia, expected to be operational by 2027.

Terry Rudolph, one of PsiQuantum's founders, believes that quantum computers will enable significant advances, just as the Industrial Revolution did when we gained the ability to calculate and simulate the laws of Newtonian mechanics. PsiQuantum's approach uses photons, which have the advantage of maintaining quantum states for a long time but are challenging to work with due to their speed and scattering properties. The company has made progress in developing the necessary technology, including a material called barium titanate, which quickly and reliably routes light particles.

PsiQuantum is testing its systems in phases, having connected three cabinets together with 250 chips in each. The next step is to scale up the systems and see if their error correction techniques can keep up. PsiQuantum's timeline is under debate, with some reports suggesting 2027 as the target for its first full-scale quantum computer.

However, the company insists that this deadline might be misread and that it only intends for its facility to be operational by the end of next year. The Pentagon's Defense Advanced Research Projects Agency has been evaluating PsiQuantum's systems, with growing optimism about the company's chances. Joe Altepeter, former head of the program, expressed increased confidence in March 2025, stating he's more optimistic now than in the past 10 years.