Strengthening practical continuous-variable quantum key distribution against measurement angular error

The optical phase shifter that constantly rotates the local oscillator is a necessity in continuous-variable quantum key distribution systems with heterodyne detection. In previous experimental implementations, generally regarded as an ideal passive device perfectly of electromagnetic wave $90^\circ$. However, practice introduces imperfections, mainly measurement angular error, which inevitably deteriorates security practical systems. Here, we will give concrete interpretation error and corresponding entanglement-based description. Subsequently, from parameter estimation, deduce overestimated excess noise underestimated transmittance, lead to reduction final secret rate. Simultaneously, propose estimation method error. Next, analysis provided detail, effect its compensation scheme are demonstrated. We conclude severely degrades security, but proposed calibration can significantly help improve performance CV-QKD