Microsoft and Quantinuum today announced a major breakthrough in quantum error correction. Using Quantinuum’s ion trap hardware and Microsoft’s new qubit virtualization system, the team was able to perform more than 14,000 experiments without a single error. This new system also allowed the team to verify logical qubits and correct any errors encountered without destroying the logical qubits.
According to the two companies, this helped bring cutting-edge quantum computing out of what has generally been dubbed the era of noisy intermediate-scale quantum computers (NISQ). “Noisy” because even the smallest changes in the environment can lead a quantum system to become essentially random (or “decohered”), and “intermediate-scale” because the current generation of quantum computers is still limited to a little more than a thousand qubits at best. . A qubit is the fundamental unit of computation in quantum systems, analogous to a bit in a classical computer, but each qubit can be in multiple states at the same time and does not fall into a specific position until it is measured, which underpins quantum’s potential to enable a huge leap forward in computing power.
However, it doesn’t matter how many qubits you have if you barely have time to run a basic algorithm before the system becomes too noisy to get a useful result – or any result at all.
By combining several different techniques, the team was able to perform thousands of experiments with virtually no errors. This involved quite a bit of preparation and pre-selection systems that already seemed in good shape for a successful race, but it is nonetheless a vast improvement over where the industry was just a short time ago.
This is a step in the right direction for quantum computing. There are still a lot of problems to solve (and these results also need to be reproduced, of course), but in theory, a computer with 100 of these logical qubits could already be useful in solving some problems, while a machine with 1,000 logical qubits could already be useful in solving certain problems. could, according to Microsoft, “unlock business advantage.”
Gaps (errors) between entangled qubits. Divergences are revealed by comparing images of each qubit in a pair, and any existing differences appear as dots in the central image between each pair. Image credits: Microsoft
The team used Quantinuum’s H2 trapped iron processor and was able to combine 30 physical qubits into four highly reliable logical qubits. Encoding multiple physical qubits into a single logical qubit helps protect the system against errors. Physical qubits are entangled so that it becomes possible to detect an error in a physical qubit and correct it.
It is this error correction that has long vexed the industry: the lower the noise and the higher the quality of physical qubits, the better, of course, but without sophisticated error correction it does not There is no way out of the NISQ era because these systems all fail sooner or later.
“There is no point in simply increasing the number of physical qubits with a high error rate, without improving that error rate, because that would result in a large quantum computer that would be no more powerful than before,” he said. said Dennis Tom, general manager of Azure. Quantum and Krysta Svore, vice president of advanced quantum development at Microsoft, write in today’s announcement. “In contrast, when physical qubits with sufficient performance quality are used with a specialized orchestration and diagnostic system to activate virtual qubits, increasing the number of physical qubits results in powerful, fault-tolerant quantum computers , capable of operating longer. , more complex calculation.
It was only a few years ago that logical qubits began to outperform physical qubits. Today, Microsoft and Quantinuum claim that their new hardware/software system has the largest gap between physical and logical error rates, improving by up to 800 times when using physical qubits alone.
Image credits: Microsoft
The researchers note that to move beyond NISQ, a large separation between the error rates of logical and physical qubits is needed, as well as the ability to correct individual circuit errors and generate entanglement between at least two qubits logical. If these results hold, then the team has achieved all three and we have indeed entered a stable era the era of resilient quantum computing.
It turns out that the most important outcome here might actually be the team’s ability to perform “active syndrome extraction,” that is, the ability to diagnose an error and correct it, without destroy the logical qubit in the process.
“This achievement marks the first step toward being able to correct errors without destroying logical qubits and is a fundamental step in correcting quantum errors,” Tom and Svore explain. “We demonstrated this essential element of reliable quantum computing with our qubit virtualization system, resulting in a low logic error rate over multiple cycles of syndrome extraction.”
It will now be up to the rest of the quantum community to replicate these results and implement similar error correction systems. But it’s probably just a matter of time.
“Today’s results mark a historic achievement and are a wonderful reflection of how this collaboration continues to push the boundaries of the quantum ecosystem,” said Ilyas Khan, Founder and Chief Product Officer at Quantinuum. “With Microsoft’s industry-leading error correction aligned with the world’s most powerful quantum computer and a fully integrated approach, we are very excited about the next evolution of quantum applications and can’t wait to see how our customers and partners will do it. benefit from our solutions, especially as we move towards large-scale quantum processors.
For more details, you can find the technical document here.
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