Fault-Tolerant Thresholds for the Surface Code in Excess of 5% under Biased Noise
David K Tuckett1, Stephen D Bartlett1, Steven T Flammia1
1Centre for Engineered Quantum Systems, School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia.
Physical Review Letters
|April 18, 2020
Summary
Quantum error correction uses tailored surface codes and efficient decoders to combat noise. This research introduces a high-threshold decoder that improves fault-tolerant performance, especially with biased dephasing noise.
Area of Science:
- Quantum computing
- Quantum error correction
- Surface codes
Background:
- Noise is a major obstacle in quantum computing, necessitating quantum error correction.
- Realistic noise often exhibits bias, particularly towards dephasing, which impacts code performance.
- Tailoring quantum error correction codes and decoders to specific noise characteristics is crucial for optimal performance.
Purpose of the Study:
- To introduce an efficient, high-threshold decoder for a noise-tailored surface code.
- To address the challenge of biased noise, specifically dephasing, in quantum computing.
- To generalize the decoder for fault-tolerant regimes with unreliable measurements.
Main Methods:
- Developed a decoder for a noise-tailored surface code based on minimum-weight perfect matching.
- Exploited syndrome symmetries under biased noise action.
- Generalized the decoder to the fault-tolerant regime with unreliable measurements.
Main Results:
- Achieved fault-tolerant thresholds exceeding 6% for a phenomenological noise model with dominant dephasing.
- Demonstrated sustained performance gains even with modest noise biases.
- Reported a threshold of approximately 5% in an experimentally relevant regime with a 100:1 dephasing to bit-flip error rate.
Conclusions:
- The developed decoder offers significant improvements in fault-tolerant thresholds for surface codes under biased noise.
- This approach is effective in mitigating dephasing-dominant noise, a common scenario in quantum systems.
- The findings pave the way for more robust quantum error correction strategies tailored to realistic noise environments.
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