The list of challenges preventing quantum computing from commercial viability is considerable, but most difficulties revolve around the error prone nature of qubits, the huge amount of power required to support these systems, and the size of these hulking quantum systems.
In a major step forward in this emerging tech, researchers at Canadian startup Nord Quantique say they’ve developed the technology to make advances on each of these fronts. First, they’ve develop a system that provides qubits with built-in error correction. This development allows quantum systems to be built at a more manageable size because they would not require the huge clusters of physical qubits that currently enable quantum computing to be fault-tolerant.
Additionally, the Nord Quantique architecture lowers the energy needs of quantum systems by using a superconducting aluminum cavity which is cooled to a very chilly absolute zero. Called a bosonic resonator, this cavity holds photons— the fundamental particles that make up light—that store quantum data in electromagnetic patterns, or modes, each of which allows the distribution of data.
The key advantage is that if a single mode is disrupted (causing errors in the qubit) the other modes offer enough data correction to support a coherent data state. This multimode data encoding, called tesseract multimode states, provides sufficient qubit fault tolerance so that less physical qubits are required. Significantly, the Nord Quantique systems supports a balanced 1:1 ratio of logical and physical qubits.
The team at Nord Quantique claim that a 1,000-qubit system using their design would fit within 20 square meters and—most important—require only a small percentage of the electrical power needed by today’s most advanced systems.
The company demonstrated its technology using a technique called post-selection to filter out imperfect runs; additionally, 12.6% of the data was discarded each round. The results showed high levels of stability in the quantum data, and no decay through 32 error correction cycles, a result that represents a major advance in the design of hardware for quantum systems.
“The amount of physical qubits dedicated to quantum error correction has always presented a major challenge for our industry,” said Julien Camirand Lemyre, CEO of Nord Quantique. “Multimode encoding allows us to build quantum computers with excellent error correction capabilities, but without the impediment of all those physical qubits.”
The company now sees a viable method for delivering fault-tolerant quantum computing as a true working solution, which is considered by many experts to be still on the horizon. Nord Quantique plans to continue to boost its results by using additional modes to improve quantum computing error correction. It expects to build its first utility-scale quantum system with more than 100 qubits by 2029.
Given the major advances the company has announced, it’s important to receive external validation of its work. Yvonne Gao, Assistant Professor at the National University of Singapore and Principal Investigator at the Centre for Quantum Technologies, said she was “pleased to see the progress by the team at Nord Quantique,” after its work on developing multimode operations in superconducting cavities.
“Their approach of encoding logical qubits in multimode Tesseract states is a very effective method of addressing error correction and I am impressed with these results,” she said. “They are an important step forward on the industry journey toward utility-scale quantum computing.”
