You are cordially invited to the following PhD. Thesis Defense Seminar by Çağın Ekici.

Title: A Study on Entangled Photon Pairs in Graded-Index Optical Fibers

Date & Time: Tuesday, July 6th, 2021, 14:00

Abstract: The main objective of the thesis is to present a study of spontaneously arisen entangled photon pairs which play crucial role in the emerging quantum enhanced technologies, such as quantum computation and quantum communication. We have mainly investigated discrete transverse-spatial-mode entangled photon pairs in waveguide, because it offers infinite dimension. In the context of heralded photon-pair source based on waveguiding, we have exploited a graded-index optical fiber as a photon pair generation platform via nonlinear intermodal four-wave mixing (FWM). Graded-index optical fibers may allow different FWM processes to overlap in the spectral domain, resulting in entangled pair of spatial qubits. We have also probed joint spectral properties of the generated photons to show capability of hyperentanglement in frequency and transverse mode. With the emphasis on transverse-mode entanglement, we have discussed spatial Wigner function and its realization to characterize spatial properties of the quantum state. We have shown that entanglement can be verified through a violation of the Clauser – Horne – Shimony – Holt inequality based on the spatial Wigner function. The thesis also includes a basic analysis of transverse-mode entangled pairs distribution including optical losses dominated by scattering and intermodal dispersion.