Nord Quantique has announced what it calls a breakthrough in quantum physics that will make quantum error correction a bit better. Errors are the top obstacle today preventing the industry from having usable quantum computers, since the individual qubits are prone to mistakes and degradation.
Typically, quantum computing companies address the error problem with redundancy. They add extra qubits to compensate for those that go off the rails. The problem is that the more qubits, the faster the errors multiply, and the more additional qubits the computer needs to compensate for.
Getting to a point where adding new qubits lowers the error rate is the break-even point, what some experts call the “escape velocity” for quantum computing. Several companies have claimed to reach this point, though, without seeing them build large-scale quantum computers there’s no way to really know for sure.
Nord Quantique claims to be one of the companies to have reached this point.
Their trick? To create a qubit that holds multiple photons inside, and then use the redundant photons for error correction. They claim that this reduces the need to have any extra qubits, making it possible to build large, usable, quantum computers.
According to quantum computing expert Bob Sutor, founder and CEO at Sutor Group Intelligence and Advisory, it takes, on average, 1,000 redundant qubits to error-correct one qubit.
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.
With the current technology, a single chandelier will be able to support more than 2,000 qubits, says Lemyre. So how close is the industry to seeing a working Nord Quantique quantum computer? Not that close.
Even though DARPA selected Nord Quantique for its quantum benchmarking initiative in April — one of fewer than 20 companies chosen — an actual computer is still years away. “We expect to have more than 100 logical qubits by 2029,” says Lemyre. “And then scaling from there to 2,000.”
That’s a long wait. But, according to Sutor, Nord Quantique technology could make an impact earlier. “It could be a technology that is ultimately adopted by other players,” he says.
Nord Quantique makes superconducting qubits, he says, just like IBM, Google, and Rigetti. That means its redundant-photons-in-a-qubit approach could be adopted by someone who is further along by swapping in the better qubit but keeping the rest of the architecture the same.
“You always have to ask with startups — are they going to be a great, big, huge company or is someone going to buy them?” he says. he new breakthrough does make their approach more attractive, he says — and shows that DARPA was right in picking the company for their initiative.
Nord Quantique’s news isn’t the only big recent announcement from a quantum computing company.
D-Wave, which uses an older and less flexible approach to quantum computing, announced record-high $15 million in revenues for the first quarter of this year, a 509% increase from this time last year, along with commercial deployments in the automotive, pharma, and defense verticals.
In general, over the first quarter of this year, private investment in quantum computing reached $1.2 billion, up 125% year-over-year, according to data from The Quantum Insider’s Intelligence Platform.
Notable investments include $360 million in IonQ, $230 million in QuEra Computing, $170 million in Quantum Machines, $150 million in D-Wave Systems, and 100 million Euros in Alice & Bob.
Another significant announcement was that of a rack-mountable, silicon-based quantum computer. Equal1’s computer has its own built-in cooling system, weights 440 pounds, and only has six qubits. Still, at about the size of a GPU server, it can fit into a regular data center.
Finally, earlier this month, Cisco announced a quantum entanglement chip. The research prototype, developed in cooperation with University of California, Santa Barbara, generates pairs of entangled photons that instantly transmit quantum state between each other, regardless of the distance between them.
Source:: Network World