The quobit breakthrough could facilitate the creation of quantum computers

A Canadian quantum calculation start-up claims that its new qubit will allow quantum computers without much smaller and cheaper error. But getting there will be a steep challenge.

To correct its own mistakes, a traditional computer records duplicates of information in several places, a practice called redundancy. In order for quantum computers to obtain their own version of redundancy, they generally require many additional quantum bits, or qubits – hundreds of thousands of them.

Now, Julien Camirand Lemyre at North Quantum and his colleagues have created a qubit which, according to them, will allow them to reduce this number to a few hundred. “The basic underlying idea behind our equipment is … to have qubits that have intrinsic redundancy,” he says.

There are several competing versions of qubits, such as tiny superconductive circuits and extremely cold atoms. The quantum northern qubit is a superconductive cavity filled with microwave radiation: the particles that transport this radiation, the photons, are trapped inside the cavity where they bounce back and back, and the information can be coded in their quantum states.

Similar qubit conceptions have already been built, but the news is the first with a “multimod coding”. This means that researchers have used several of the photon properties both to store information – a encoding method that makes this data more resilient at current quantum computer errors.

Victor Albert at the University of Maryland says that the quantum error correction requires more qubits – so that the information can be stored in a group of connected qubits rather than one, protecting the system of failure of any individual qubit – or so that each qubit is “greater” in the sense of the way the information is stored inside.

The new QUEBIT uses the second technique, storing information in a mathematical space which is actually four dimensions, he says.

For this reason, North Quantum provides that its tolerant quantum computers with breakdowns will be up to 50 times smaller than those that use qubits made from superconductive circuits, as the most advanced built to date. In addition, the company considers that the machines built with its qubits will consume only tenth as much energy as these other machines.

However, North Quantum has not yet presented data on more than one qubit. He also did not use his new qubit in a calculation, other than to verify that he indeed takes the multimode coding. Many stages and technical challenges remain on the road to the team to quantum computer on a large scale.

“It is too early to say if this approach to the tolerant calculation for faults … is intrinsically more advantageous than some of the other approaches sought,” explains Barbara Terhal at the University of Delft technology in the Netherlands.

Michel Devoret at the University of Yale says that the new work is “an incremental, rather than revolutionaries, leads to the science of correction of quantum errors”, but it shows the mastery of the technical challenges of the company.

Lemyre says they are now working on the construction of more qubits and improving their current design. For example, they want to add “improvement mechanisms” that handle the information stored in the QUBIT, as it must occur when a quantum computer performs a calculation. They expect to build a practical quantum computer with more than 100 of their quits resilient to errors by 2029.