Good news!
"... Today [4/3/2024], Microsoft is announcing a critical breakthrough that advances the field of quantum computing by improving the logical error rate by 800x when compared to the error rate on corresponding physical qubits, thus creating the most reliable logical qubits to date. ...
With our qubit-virtualization system, we were able to create four highly reliable logical qubits from only 30 physical qubits of the available 32 on Quantinuum’s machine. When entangled, these logical qubits exhibited a circuit error rate of 10-5 or 0.00001, which means they would experience an error only once in every 100,000 runs. That is an 800x improvement over the circuit error rate of 8×10-3 or 0.008, measured from entangled physical qubits. This result was achieved through a combination of advanced runtime error diagnostics with computational run rejection and error correction. ..."
The results presented here were achieved by coupling Microsoft’s qubit-virtualization system with Quantinuum’s specialized hardware. Quantinuum’s H-Series ion-trap qubits and unique Quantum Charged Coupled Device architecture have an excellent two-qubit gate fidelity of 99.8%. By applying our qubit-virtualization system to their qubits, we have been able to run 14,000 independent instances so far without a single error. Our sophisticated system has error diagnostics and corrections built in, allowing us to easily determine which errors need to be fixed and how to fix them.
From the abstract:
"The promise of quantum computers hinges on the ability to scale to large system sizes, e.g., to run quantum computations consisting of roughly more than 100 million operations fault-tolerantly. This in turn requires suppressing errors to levels inversely proportional to the size of the computation. As a step towards this ambitious goal, we present experiments on a trapped-ion QCCD processor where, through the use of fault-tolerant encoding and error correction, we are able to suppress logical error rates to levels below the physical error rates. In particular, we show Bell states encoded in the [[7,1,3]] code with error rates 9.8 to 500 times lower than at the physical level, and Bell states encoded in a [[12,2,4]] code with error rates 4.7 to 800 times lower than at the physical level, depending on the judicious use of post-selection. Moreover, we demonstrate repeated error correction with the [[12,2,4]] code, with logical error rates below physical circuit baselines corresponding to repeated CNOTs, and show evidence that the error rate per error correction cycle, which consists of over 100 physical CNOTs, approaches the error rate of two physical CNOTs. These results signify an important transition from noisy intermediate scale quantum computing to reliable quantum computing, and demonstrate advanced capabilities required for large-scale fault-tolerant quantum computing."
How Microsoft and Quantinuum achieved reliable quantum computing (original news release) By applying an innovative qubit-virtualization system to ion-trap hardware, Microsoft and Quantinuum were able to create four highly reliable logical qubits from only 30 physical qubits, while demonstrating an 800x improvement in error rate.
Demonstration of logical qubits and repeated error correction with better-than-physical error rates (open access)
Figure 1: A depiction of the preparation we used to entangle qubits. The portion inside the dashed line is a rough representation of the circuit used to create the entangled state. A and B represent measurements that can be applied to each half of the state. In the absence of errors, the outcome on one half should agree with the outcome on the other half, if the types of measurement applied to each half are the same. Impressively, after this procedure was run 14,000 times, there were no disagreements between the measurement outcomes.
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