High speed error correction for continuous-variable quantum key distribution with multi-edge type LDPC code.

Area of Science:

• Quantum Information Science
• Information Theory
• Computer Engineering

Background:

• Error correction is crucial for secure key sharing in continuous-variable quantum key distribution (CV-QKD).
• Efficient postprocessing is needed to achieve high-speed, real-time CV-QKD systems.
• Traditional error correction methods can be computationally intensive, limiting system speed.

Purpose of the Study:

• To experimentally demonstrate high-speed error correction for CV-QKD.
• To leverage graphic processing units (GPUs) for accelerating decoding of multi-edge type low-density parity check (MET-LDPC) codes.
• To optimize MET-LDPC decoding algorithms and memory structures for enhanced computational efficiency.

Main Methods:

• Implementation of MET-LDPC codes on a GPU for parallel message calculation and codeword decoding.
• Optimization of the parity check matrix memory structure to reduce computational complexity.
• Refinement of the belief propagation decoding algorithm for improved performance.

Main Results:

• Achieved average error correction speeds of 30.39 Mbits/s (0.1 code rate), 21.23 Mbits/s (0.05 code rate), and 16.41 Mbits/s (0.02 code rate) with block length 10^6.
• Demonstrated over three times speed improvement compared to previous error correction methods.
• Successfully decoded 64 codewords in parallel, supporting high-speed real-time CV-QKD.

Conclusions:

• GPU-accelerated MET-LDPC decoding significantly enhances error correction speed in CV-QKD systems.
• The optimized decoding algorithm and memory structure contribute to the substantial speedup.
• This approach enables high-speed, real-time CV-QKD, advancing secure communication technologies.