Creating heralded hyper-entangled photons using Rydberg atoms

• Published in: Light, science & applications science & applications, 2021-05, Vol.10 (1), p.100-100, Article 100
• Main Authors: Ghosh, Sutapa, Rivera, Nicholas, Eisenstein, Gadi, Kaminer, Ido
• Format: Article
• Language: English
• Subjects: 639/624/400/1100; 639/624/400/482; Applied and Technical Physics; atom optics; Atomic; ATOMIC AND MOLECULAR PHYSICS; Atoms & subatomic particles; Classical and Continuum Physics; Lasers; Molecular; Optical and Plasma Physics; Optical Devices; Optics; Photonics; Photons; Physics; Physics and Astronomy; quantum optics; Rubidium
• ISSN: 2047-7538; 2095-5545; 2047-7538
• DOI: 10.1038/s41377-021-00537-2

Entangled photon pairs are a fundamental component for testing the foundations of quantum mechanics, and for modern quantum technologies such as teleportation and secured communication. Current state-of-the-art sources are based on nonlinear processes that are limited in their efficiency and wavelength tunability. This motivates the exploration of physical mechanisms for entangled photon generation, with a special interest in mechanisms that can be heralded, preferably at telecommunications wavelengths. Here we present a mechanism for the generation of heralded entangled photons from Rydberg atom cavity quantum electrodynamics (cavity QED). We propose a scheme to demonstrate the mechanism and quantify its expected performance. The heralding of the process enables non-destructive detection of the photon pairs. The entangled photons are produced by exciting a rubidium atom to a Rydberg state, from where the atom decays via two-photon emission (TPE). A Rydberg blockade helps to excite a single Rydberg excitation while the input light field is more efficiently collectively absorbed by all the atoms. The TPE rate is significantly enhanced by a designed photonic cavity, whose many resonances also translate into high-dimensional entanglement. The resulting high-dimensionally entangled photons are entangled in more than one degree of freedom: in all of their spectral components, in addition to the polarization—forming a hyper-entangled state, which is particularly interesting in high information capacity quantum communication. We characterize the photon comb states by analyzing the Hong-Ou-Mandel interference and propose proof-of-concept experiments.