Error-Control Information Reconciliation Scheme for Continuous-Variable Quantum Key Distribution Using Fixed-Bit Polar Codes

A challenging issue in continuous-variable quantum key distribution (CV-QKD) is the improvement in error correction efficiency because random number bits are encoded in a quadrature of faint optical pulses. Herein, we propose an error-control information reconciliation method for CV-QKD based on our recently proposed fixed-bit polar code. In the present scheme, unreliable bits are embedded in the prepared “fixed bits,” enabling the detection and reproduction of errors in these bits without error correction, effectively improving the error-correction efficiency. Numerical simulations demonstrate that the efficiency of the proposed scheme is 10% higher than that of polar code-based reconciliation without fixed bits.