High-speed and Large-scale Privacy Amplification Scheme for Quantum Key Distribution.

Area of Science:

• Quantum Information Science
• Cryptography
• Computational Mathematics

Background:

• State-of-art quantum key distribution (QKD) systems operate at GHz pulse rates, necessitating efficient privacy amplification (PA) for secure key generation.
• Current PA methods struggle with large-scale inputs required for quantified security in high-speed QKD.
• Dedicated computational hardware often increases system complexity and cost.

Purpose of the Study:

• To propose a novel privacy amplification scheme that enhances speed and scalability for QKD systems.
• To implement this scheme on commercial CPUs without requiring additional dedicated hardware.
• To evaluate the performance of the proposed scheme with large input scales and varying compression ratios.

Main Methods:

• Developed a Fast Fourier Transform (FFT) enhanced high-speed and large-scale (HiLS) PA scheme.
• Implemented parallel processing by dividing secure keys into blocks and shuffling random seeds for Toeplitz matrix construction.
• Merged outcomes from parallel PA procedures to generate the final secure key.

Main Results:

• Achieved throughputs of 71.16 Mbps (0.125 compression), 54.08 Mbps (0.25 compression), and 39.15 Mbps (0.375 compression) for 128 Mb input scale.
• Demonstrated applicability to 10 GHz QKD systems with 1 Gb input, reaching 32.49 Mbps (0.125 compression), a tenfold increase over previous works.
• Showcased efficiency on limited computational resources, achieving 0.44 Mbps (0.125 compression) for 128 Gb input scale.

Conclusions:

• The proposed HiLS PA scheme significantly enhances secure key generation rates for QKD systems on commercial CPUs.
• The method achieves high throughput and scalability, approaching asymptotic limits for secure key generation.
• The FFT-enhanced PA scheme is also theoretically applicable and efficient for randomness extraction in high-speed quantum random number generation (QRNG).