Advancements in Quantum Error Correction Techniques

Recent advancements in quantum error correction have been reported in a paper titled "Quantum error correction below the surface code threshold" by Rajeev Acharya and 248 co-authors. The research presents two surface code memories that operate effectively below the critical error threshold necessary for practical quantum computing. These include a distance-7 code and a distance-5 code, both integrated with a real-time decoder. The findings indicate that the logical error rate of the larger quantum memory is suppressed by a factor of 2.14 when the code distance is increased by two. This results in a 101-qubit distance-7 code achieving an error rate of 0.143% per cycle of error correction.

The study highlights that the logical memory performance exceeds the best physical qubit's lifetime by a factor of 2.4. Additionally, the researchers maintained below-threshold performance while decoding in real time, achieving an average decoder latency of 63 microseconds at distance-5 over a million cycles, with a cycle time of 1.1 microseconds.

To further explore the limits of error-correction performance, the team conducted tests with repetition codes up to distance-29. They found that logical performance is constrained by rare correlated error events occurring approximately once every hour, or every 3 billion cycles. The results suggest that if these advancements can be scaled, they could meet the operational requirements for large-scale fault-tolerant quantum algorithms, which is a significant step towards practical quantum computing applications.