Ultrafast Processing of Hyper-Entangled Bell States at the Optical Bandwidth Limit

Abstract

Bell states embody the most basic form of two-state entanglement and are a key component of quantum protocols of communication and sensing, indicating that high-speed processing of polarization Bell-states is highly desired for quantum technology. Yet, the processing speed of all current protocols is inherently limited by the electronic bandwidth of photo-detectors (Photomultiplier tubes, avalanche photo-diodes, etc.) that can process only $10^{6-7}$ photons/s, whereas standard broadband sources may easily produce $10^{10-14}$ photons/s. Using dual polarization, nonlinear SU(1,1) interferometry as an ultrafast quantum detector of the entangled bi-photons, we demonstrate the complete cycle of processing - generation, manipulation \textit{and detection} of polarization-entangled Bell states at an ultra-high photon-flux of $\sim 5\times 10^{11}$ photons/s ($\sim 5$ orders of magnitude higher than standard methods), limited only by the optical bandwidth of the generating source.

arXiv comment5 Pages, 4 figures