one that calculates with particles of light

In the south of Chicago, on the grounds of a former steel plant, a 6,000-square-meter building is being built that could house the first quantum computer fault-tolerant and useful world scale. Those responsible are PsiQuantuma Palo Alto startup that has decided to go for something that almost no one else is trying: build this machine using light particles.

Why is it important. Quantum computing has been promising for decades to solve problems that would take current computers millions of years, from designing new drugs to simulating materials or batteries. The problem is that, so far, the existing prototypes are too small and pprone to errors to be useful.

PsiQuantum wants to skip that intermediate phase and directly build a large-scale machine, according to explained its CEO, Victor Peng, in an interview with Fast Company.

light particles. While giants like IBM, Google or Amazon build their qubits (the basic unit of quantum information) with superconducting circuits, and other companies use ions or trapped atoms, PsiQuantum has opted for photons, particles of light. It is a way that Share only with the Canadian Xanadu among the major players in the sector, according to collect MIT Technology Review.

The advantage, according to Terry Rudolphone of the four physicists who founded the company in 2016, is that photons can maintain their quantum state for a long time. The drawback is that they barely interact with each other, which is essential for doing calculations. The solution to this problem came in 2001, when a team from Los Alamos and the University of Queensland discovered that these interactions could be “simulated” by sending light through a network of mirrors and detectors. This discovery is the basis on which all PsiQuantum technology is based.

A large project. Unlike its competitors, which are gradually expanding larger and larger computers, PsiQuantum has focused almost all of its efforts on suddenly developing the technology and manufacturing capacity necessary for a huge system of around one million physical qubits. The company needs to have “almost the entire process running” before building its first machine, which lengthens initial times, according to admits Peng to the middle. However, he argues that this later facilitates replication on a larger scale.

To achieve this, PsiQuantum manufactures its own chips together with the semiconductor giant GlobalFoundries, etched with channels that direct light instead of wires, and incorporates a ceramic compound called barium titanate that allows photons to be switched with great precision. Another advantage of betting on light is that only one part of the machine, the detectors that measure photons, needs to be cooled to temperatures close to absolute zero, while other quantum technologies require cooling the entire system, according to they count from MIT Technology Review.

Rpolitical support. Illinois Governor JB Pritzker has promoted the Illinois Quantum and Microelectronics Park with $500 million in state funds to turn the area into a hub for quantum computing, similar to what the Stanford Research Park was for Silicon Valley. Pritzker explained to Fast Company that does not want to repeat the mistake of the nineties, when talent trained at Illinois universities, such as the creators of the Mosaic browser, ended up leaving for California. The park already has six other tenants committed, including IBM, and will also host a test program for the defense agency DARPA.

And now what. PsiQuantum, which has already raised more than $1 billion in financing and has received $100 million from the US Government through the CHIPS Act, is also building a second plant in Brisbane, Australia. The company has lowered expectations regarding deadlines, as it no longer promises to have a functional quantum computer ready in 2027, but rather that its facilities are “operational”, that is, with the cooling systems ready to install the hardware, according to they claim from the middle.

DARPA, which has been evaluating the company’s technology since 2023, has been increasingly optimistic about the sector. And its current manager, Micah Stoutimore, has even stated that someone could build a quantum computer of a useful scale “around 2033.” If PsiQuantum meets its deadlines, Chicago could become the birthplace of that machine.

Cover image | Winni Wintermeyer (MIT Technology Review)

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