Versatile photonic entanglement synthesizer in the spatial domain

TL;DR

This paper demonstrates that an integrated array of nonlinear waveguides can serve as a versatile, scalable source of multimode entanglement and cluster states in the spatial domain for continuous-variable quantum information processing.

Contribution

It introduces a compact integrated device capable of generating and manipulating multimode entanglement without bulk optics, enhancing scalability and versatility in quantum photonics.

Findings

Analytical and numerical demonstration of multimode squeezing and entanglement

Generation of cluster states in various encodings

Re-establishment of spatial encoding as a viable quantum information platform

Abstract

Multimode entanglement is an essential resource for quantum information in continuous-variable systems. Light-based quantum technologies will arguably not be built upon table-top bulk setups, but will presumably rather resort to integrated optics. Sequential bulk optics-like proposals based on cascaded integrated interferometers are not scalable with the current state-of-the-art low-loss materials used for continuous variables. We analyze the multimode continuous-variable entanglement capabilities of a compact currently-available integrated device without bulk-optics analog: the array of nonlinear waveguides. We theoretically demonstrate that this simple and compact structure, together with a reconfigurable input pump distribution and multimode coherent detection of the output modes, is a versatile entanglement synthesizer in the spatial domain. We exhibit this versatility through analytical and numerically optimized multimode squeezing, entanglement, and cluster state generation in different encodings. Our results re-establish spatial encoding as a contender in the game of continuous-variable quantum information processing.