Quantum mechanics

Bandwidth (computing)

Telecommunications

Computer science

Spontaneous parametric down-conversion

Nanophotonics

Quantum optics

Photon

Quantum sensor

Physics

Photon entanglement

Quantum entanglement

Optics

Quantum network

Terahertz radiation

Lithium niobate

Quantum

Optoelectronics

Physical Review Letters

The development of quantum technologies on nanophotonic platforms has seen momentous progress in the past decade. Despite that, a demonstration of time-frequency entanglement over a broad spectral width is still lacking. Here we present an efficient source of ultrabroadband entangled photon pairs on a periodically poled lithium niobate nanophotonic waveguide. Employing dispersion engineering, we demonstrate a record-high 100 THz (1.2 μm-2 μm) generation bandwidth with a high efficiency of 13 GHz/mW and excellent noise performance with the coincidence-to-accidental ratio exceeding 10^{5}. We also measure strong time-frequency entanglement with over 98% two-photon interference visibility.

Ultrabroadband Entangled Photons on a Nanophotonic Chip