DOI: 10.22184/1993-7296.FRos.2024.18.4.282.294

All-­Russian Research Institute of Optical and Physical Measurements (VNIIOFI), Moscow, Russia
The paper analyzes the efficiency of a quantum state fidelity to assess the raw bit error value introduced by the polarization state of a single photon source. The analysis was performed for the quantum key distribution schemes BB84 and BBM92. It has been shown theoretically and experimentally that when the fidelity is decreased from 1 to 0 in the BB84 scheme, the raw bit error value linearly increases from 0 to 1, and in the BBM92 scheme – ​from 0 to 1/2. The experimental setups for determine the influence of fidelity on the bit error value are described in detail.