Nord Quantique claims error-correcting quantum physics breakthrough

The industry calls this “logical qubits” — so, on average, 1,000 physical qubits is equivalent to one usable, working logical qubit.  In Nord Quantique’s approach, one physical qubit is the same as one logical qubit.

“It’s almost like turning the error correction problem inside out,” says Sutor. “Instead of having redundant qubits on the outside to create one good logical qubit, you’re focusing on the inside of the qubit.”

According to Sutor, quantum computers get interesting at around 100,000 qubits. At a ratio of 1,000-to-one, that will require 100 million physical qubits to accomplish. Today’s most advanced quantum computers have less than 1,200 qubits.

By reducing the ratio, quantum computers would need a thousand times fewer qubits, making them significantly easier to build and scale, while also requiring less power and computational error-correction overhead.  Last year, Nord Quantique demonstrated that their multiple-photons-in-a-single-qubit approach was feasible, creating qubits with up to 30 photons inside.

The limitation then was that their error correcting photons were only able to compensate for a single type of error. In today’s announcement, they’ve figured out how to compensate for a second type of error, by adding an additional mode to the qubit. This makes the qubit more resilient and accurate, and opens the path to add even more error-correcting modes in the future.

According to Nord Quantique CEO Julien Camirand Lemyre, each qubit is a cubic millimeter and size. Since the company uses the superconducting approach to quantum computing, it still needs that giant chandelier to get the system cool enough, which takes about 20 square meters of floor space.