In an experimental demonstration using a superconducting processor named Zuchongzhi 3.2, China has announced a significant advancement in quantum error correction, dubbed “quantum supremacy 2.0.”
Zuchongzhi 3.2 processor successfully operates a surface-code logical qubit at a distance 7.
The noteworthy factor is that as the code distance increases, the logical error rate decreases. This inverse relation is a critical aspect of China’s latest quantum error correction technique that rivals Google’s earlier achievements with its Willow results.
What sets China’s claim apart is an all-microwave leakage suppression architecture designed to minimise “leakage,” where qubits escape the computational states assumed by error-correcting codes.
Addressing leakage is crucial, as it can lead to correlated failures that traditional decoders struggle to manage. This new method makes leakage control a vital design consideration, as previous research also advocated for its importance in maintaining clean surface-code cycles.
While China’s results aim to match Google’s benchmarks, they do not yet demonstrate the capability to run large computations on multiple interacting logical qubits.
Transitioning from a single logical qubit to many brings complex engineering challenges and new error pathways.
IBM’s roadmap emphasises that scaling to practical fault-supressing systems will require efficient codes and real-time decoding pipelines.
As the industry is adopting the “error correction era,” the focus is shifting to make error correction repeatable, automatable, and economically scalable.
With multiple groups achieving below-threshold behaviour, the next challenge is expected to lie in efficiently stacking logical qubits and maintaining manageable error budgets during actual computations.
