Spatial-spectral mapping to prepare the frequency entangled qudits

TL;DR

This paper introduces a novel method for efficiently preparing high-dimensional frequency entangled qudits using spatial-spectral mapping in spontaneous parametric downconversion, demonstrated experimentally with a three-dimensional state.

Contribution

The paper presents a new approach employing angle-dependent phase-matching to engineer frequency entangled qudits via spatial-spectral mapping, simplifying high-dimensional entanglement preparation.

Findings

Successfully generated a three-dimensional frequency entangled state.

Demonstrated a feasible and efficient method for high-dimensional entanglement.

Utilized a homemade variable slit mask for experimental validation.

Abstract

Entangled qudits, the high-dimensional entangled states, play an important role in the study of quantum information. How to prepare entangled qudits in an efficient and easy-to-operate manner is still a challenge in quantum technology. Here, we demonstrate a method to engineer frequency entangled qudits in a spontaneous parametric downconversion process. The proposal employs an angle-dependent phase-matching condition in a nonlinear crystal, which forms a classical-quantum mapping between the spatial (pump) and spectral (biphotons) degrees of freedom. In particular, the pump profile is separated into several bins in the spatial domain, and thus shapes the down-converted biphotons into discrete frequency modes in the joint spectral space. Our approach provides a feasible and efficient method to prepare a high-dimensional frequency entangled state. As an experimental demonstration, we generate a three-dimensional entangled state by using a homemade variable slit mask.