This paper presents an integrated experimental platform for polarization-based BB84 quantum key distribution (QKD) demonstration and repeatable optical experiments. The platform integrates automated laser control, polarization-state selection, photodiode-based detection, data logging, and web-based key processing into a unified experimental workflow. Experimental evaluation achieved average BER values below 2% for all four BB84 polarization states. In an end-to-end experiment with 33,000 transmitted bits, the overall QBER was 1.49%, and 5,341 final key bits were obtained after privacy amplification. Furthermore, ten consecutive QKD sessions were completed successfully, with an average final key length of approximately 3,353 bits per session. These results demonstrate the capability of the proposed platform to support repeatable experimental demonstration and evaluation of polarization-based BB84 QKD.

Quantum Key Distribution,BB84,polarization,optical communications,experimental platform