Assessment of Polarization Entanglement Source: Photon Counting and Correlation Measurement

TL;DR

This paper develops a comprehensive, scalable testing framework for polarization entanglement sources at telecommunication wavelengths, emphasizing measurement accuracy, component non-idealities, and practical certification methods.

Contribution

It introduces a detailed testing methodology incorporating photon counting, correlation measurements, and analysis of non-idealities for characterizing commercial entanglement sources.

Findings

Bounds for true and false coincidences established

Impact of measurement non-idealities on QBER analyzed

Comparison of quantum state tomography and direct measurement approaches

Abstract

Commercial sources of polarization entanglement at telecommunication wavelengths are already available on the market, but they lack proper certification or third-party testing. We aim to provide a comprehensive testing framework for photon counting and correlation measurements to characterize the parameters of these sources in a scalable and repeatable manner. The detection setup is included in our considerations, as the non-idealities of the components negatively affect the relevance of the measurement results. We discuss bounds for both true and false coincidences with rigorous probabilistic approach, as their ratio directly impacts the resolution of coincidence measurements and is reflected in Quantum Bit Error Rate (QBER) in the quantum telecommunication system. Quantum State Tomography (QST), polarization visibility measurements, temporal correlations measurements, and computations of other statistics are to be performed and compared at the state-of-the-art level for a three commercially available sources. Given that QST is demanding in terms of number of measurements and post-processing analysis, we discuss the relevance of determining the degree of polarization entanglement considering solely other statistics of direct measurement approach.