Generation and Detection of Hyperentangled Bell States at an Ultra-High Flux

TL;DR

This paper demonstrates the generation and detection of hyperentangled Bell states at an ultra-high flux using nonlinear interferometry, significantly surpassing traditional detection speeds and advancing quantum communication and sensing technologies.

Contribution

It introduces a method to generate, manipulate, and measure Bell states at fluxes of around 5×10^{11} photons/sec using a dual polarization SU1,1 interferometer, overcoming current detection speed limitations.

Findings

Achieved detection of Bell states at ~5×10^{11} photons/sec.

Enhanced quantum processing speed by over five orders of magnitude.

Utilized broadband hyper-entangled bi-photons in polarization and time-energy domains.

Abstract

We demonstrate both the generation and detection of an ultra-high flux of polarization Bell states using broadband hyper-entangled bi-photons that are quantum-correlated in both polarization and time-energy. Bell states of polarization embody the most basic form of two-state entanglement, and are a key component of quantum protocols of communication and sensing. High-speed generation, processing and detection of polarization Bell-states is therefore critical for quantum technology. However, all current protocols that employ polarization entangled photons are inherently slow, primarily due to the photo-detectors (Photomultiplier tubes, avalanche photo-diodes, etc.) that can handle only $10^{6-7}$ photons/s, whereas sources may easily produce $10^{10-13}$ photons/s or more (if properly designed). We fully alleviate this detection bottleneck by resorting to physical detection of the bi-photons with nonlinear interferometry. We harness a generalized, dual polarization SU1,1 interferometer to generate, manipulate \textit{and measure} all the triplet Bell-states at a flux of $\sim\!5\times10^{11}$ photons/s, enhancing the speed of quantum processing by >5 orders of magnitude compared to standard methods.