Event time:
Tuesday, August 19, 2025 - 11:00am to 12:00pm
Audience:
YQI Researchers
Location:
YQI Seminar Room
Event description:
Tailoring Dynamical codes for Biased Noise: The X3Z3 Floquet Code
Several architectures have a biased noise profile which can be exploited to achieve higher code performance. Floquet codes, meanwhile, can be particularly suitable to setups with low connectivity or native two-qubit entangling measurements, but adapting such codes to biased noise regimes has not been investigated previously. In this talk, I will introduce the X3Z3 Floquet code, a dynamical code with improved performance under biased noise compared to other Floquet codes. The enhanced performance is attributed to a simplified decoding problem resulting from a persistent stabiliser-product symmetry, which surprisingly exists in a code without constant stabilisers. Even if such a symmetry is allowed, we prove that general dynamical codes with two-qubit parity measurements cannot admit one-dimensional decoding graphs, a key feature responsible for the high performance of bias-tailored stabiliser codes. Despite this, our simulations show that the symmetry of the X3Z3 Floquet code renders its performance under biased noise far better than several leading Floquet codes. To help maintain high-performance implementation in hardware without native two-qubit parity measurements, we introduce phase-bias-preserving parity measurement circuits for two of the three check measurements. Our work establishes the X3Z3 code as a prime quantum error-correcting code candidate, particularly for devices with reduced connectivity, such as the honeycomb and heavy-hexagonal architectures.
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