Scalable scheme for entangling multiple ququarts using linear optical elements

TL;DR

This paper presents a scalable linear optical method for creating entangled states of multiple ququarts, utilizing biphoton polarization states from spontaneous parametric down-conversion, with detailed analysis including higher order effects.

Contribution

The paper introduces a new scalable scheme for entangling multiple ququarts using linear optics and biphoton states, accounting for higher order effects in the process.

Findings

Successfully demonstrated entanglement of three and four ququarts.

Analyzed the impact of double-pair events on entanglement quality.

Provided a practical approach for scalable quantum entanglement generation.

Abstract

We report a scalable linear optical scheme for generating entangled states of multiple ququarts in which the individual single-ququart state is prepared with the biphoton polarization state of frequency-nondegenerate spontaneous parametric down-conversion. The output state is calculated with the full consideration of the higher order effect (double-pair events) of spontaneous parametric down-conversion. Scalability to multiple-ququart entanglement is demonstrated with examples: linear optical entanglement of three and four individual biphoton ququarts.