  An integrated error-correction scheme with high throughput, low frame errors
rate (FER) and high reconciliation efficiency under low signal to noise ratio
(SNR) is one of the major bottlenecks to realize high-performance and low-cost
continuous variable quantum key distribution (CV-QKD). To solve this
long-standing problem, a novel two-stage error correction method with limited
precision that is suitable for integration given limited on-chip hardware
resource while maintaining excellent decoding performance is proposed, and
experimentally verified on a commercial FPGA. Compared to state-of-art results,
the error-correction throughput can be improved more than one order of
magnitude given FER<0.1 based on the proposed method, where 544.03 Mbps and
393.33 Mbps real-time error correction is achieved for typical 0.2 and 0.1 code
rate, respectively. Besides, compared with traditional decoding method, the
secure key rate (SKR) for CV-QKD under composable security framework can be
improved by 140.09% and 122.03% by using the proposed two-stage decoding method
for codes rate 0.2 and 0.1, which can support 32.70 Mbps and 5.66 Mbps
real-time SKR under typical transmission distances of 25 km and 50 km,
correspondingly. The record-breaking results paves the way for large-scale
deployment of high-rate integrated CV-QKD systems in metropolitan quantum
secure network.
