Microsoft and Quantinuum today was announced a breakthrough in quantum error correction. Using Quantinuum’s ion-trap hardware and Microsoft’s new qubit virtualization system, the team was able to run more than 14,000 experiments without a single error. This new system also allowed the team to test the logic qubits and fix any errors they encountered without destroying the logic qubits.
This, the two companies say, has now moved the state of the art of quantum computing out of what has commonly been called the era of noisy intermediate-scale quantum computing (NISQ). “Noisy” because even the smallest changes in the environment can cause a quantum system to become essentially random (or “decay”) and “intermediate scale” because the current generation of quantum computers is still limited to 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 many states at once and does not fall into a specific position until it is measured, which is the basis of the quantum possibility for to provide a huge leap in computing power.
It doesn’t matter how many qubits you have, however, if you don’t 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 many different techniques, the team was able to run thousands of experiments with virtually no errors. This involved a lot of preparation and pre-selection of systems that already seemed to be in good shape for a successful run, but still, this is a huge improvement from where the industry was a while ago.
It’s a step in the right direction for quantum computing. There are still many problems to be solved (and these results need to be reproduced, of course), but in theory, a computer with 100 of these logical qubits could already be useful for solving some problems, while a machine with 1,000 qubits could, says Microsoft, “unlock commercial advantage.”
The deviations (errors) between entangled qubits. Discrepancies are revealed by comparing the images from each qubit in a pair, and any differences that exist are shown as dots in the central image between each pair. Image Credits: Microsoft
The team used Quantinuum’s Trapped Ion Processor H2 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 from errors. Physical qubits are entangled with each other so that an error in a physical qubit can be detected and corrected.
It is this error correction that has long troubled the industry: the lower the noise and the higher the quality of the physical qubits, the better, of course, but without complex error correction, there is no way out of the NISQ era, because these systems will all de-coordinate sooner rather than later.
“Simply increasing the number of physical qubits with a high error rate – without improving that error rate – is futile, because doing so would result in a large quantum computer that is no more powerful than before,” said Dennis Tom, general manager of Azure. Quantum and Krysta Svore, Vice President of Advanced Quantum Development at Microsoft, wrote in today’s announcement. “In contrast, when physical qubits with sufficient operational quality are used with a specialized instrumentation and diagnostics system to enable virtual qubits, only then increasing the number of physical qubits leads to powerful, fault-tolerant quantum computers capable of higher performance. , more complex calculation.”
It was alone a few years ago that logical qubits began to outperform physical qubits. Now, Microsoft and Quantinuum claim their new hardware/software system exhibits the largest gap between physical and logical error rates, improving the use of only physical qubits by up to 800x.
Image Credits: Microsoft
The researchers note that to move beyond NISQ, a large separation between logical and physical qubit error rates is necessary, as is the ability to correct individual circuit errors and create entanglement between at least two logical qubits. If these results hold, then the team has achieved all three and we are indeed in one constant season in the age of durable quantum computers.
As it turns out, the most important result here may actually be the team’s ability to perform “active syndrome extraction” — that is, the ability to diagnose an error and fix it, without destroying the logic qubit in the process.
“This achievement marks the first step toward being able to correct errors without destroying the logical qubits and represents a fundamental milestone in quantum error correction,” Tom and Svore explain. “We demonstrated this critical element of reliable quantum computing with our qubit virtualization system, which resulted in a reasonably low error rate over multiple rounds of syndrome derivation.”
It will now be up to the rest of the quantum community to replicate these results and implement similar error correction systems. That’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 for the quantum ecosystem,” said Ilyas Khan, Founder and Chief Product Officer of Quantinuum. “With Microsoft’s state-of-the-art error correction aligned with the world’s most powerful quantum computer and a fully integrated approach, we are so excited for the next evolution in quantum applications and look forward to seeing how our customers and partners take advantage of our solutions, especially as we move towards quantum processors at scale.”
For more details, you can find the technical document here.
