Radial polarization imaging of entangled biphoton state

Published

June 11, 2025

Author(s)

Jiung Kim, Jeeseong Hwang, Martin Sohn

Abstract

Polarization entanglement of single photons is a key element to enable quantum 2.0 applications such as quantum computing, quantum networks, and quantum sensing. Verification and fidelity assessment of quantum entanglement of single photon pairs correlated in polarization are typically performed by sequential measurements with point single-photon counting detectors, which record coincidence counts for a series of polarization state combinations of the entangled photons, to extract quantum interference plots and ultimately test the violations of Bell's inequality. Here, we present a new rapid quantum imaging technique capable of visualizing quantum entanglement of polarization-entangled photon pairs using radial polarizations. Unlike the sequential coincidence measurement, in our technique a single-photon counting camera (SPCC) captures a single coincidence count image with multiple polarization states generated by a radial wave plate (RWP), which converts a linear polarization state of single photons to radial polarization states. The coincidence image is taken by the SPCC triggered by the idler photon in a specific polarization state. Bell's inequality is calculated directly from a set of images, which shows quantum interferences. Our technique not only visualizes parallel measurement of entangled polarization states but also enables fast full Bell-type evaluation of photonic polarization entanglement. We envision that our approach may be instrumental for developing advanced polarization-entangled photon sources and polarization-entangled quantum systems to enable fundamental research involving dynamic photon-matter interactions.

Citation

APL Photonics

Volume

10

Issue

6

Pub Type

Journals

Download Paper

https://doi.org/10.1063/5.0260101

Local Download

Keywords

Quantum imaging, polarization entanglement, entangled biphotons, quantum correlation, Bell's inequality, radial polarization, radial wave plate

Citation

Kim, J. , Hwang, J. and Sohn, M. (2025), Radial polarization imaging of entangled biphoton state, APL Photonics, [online], https://doi.org/10.1063/5.0260101, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=958568 (Accessed July 4, 2025)