Direct generation of time-energy-entangled W triphotons in atomic vapor

TL;DR

This paper demonstrates the direct generation of time-energy-entangled W-class triphotons in atomic vapor using spontaneous six-wave mixing, offering a new, efficient source for quantum communication and information processing.

Contribution

It introduces a novel method for directly producing triphotons in atomic vapor, bypassing previous multiplexing techniques, with high rate and controllable properties.

Findings

First observation of continuous-mode triphotons in atomic vapor

High generation rate of entangled triphotons achieved

Triphotons exhibit long coherence and waveform control

Abstract

Sources of entangled multiphotons are not only essential for fundamental tests of quantum foundations, but are also the cornerstone of a variety of optical quantum technologies today. Over past three decades, tremendous efforts have been devoted to creating multiphoton entanglement by multiplexing existing biphoton sources with linear optics and postselections. Different from all previous protocols, here we report, for the first time, the observation of continuous-mode time-energy-entangled W-class triphotons with an unprecedented generation rate directly through the process of spontaneous six-wave mixing (SSWM) in a four-level triple-Lambda atomic vapor cell. Facilitated by electromagnetically induced transparency and coherence control, our SSWM scheme enables versatile narrowband triphoton generation with many intriguing properties including long temporal coherence and controllable waveforms, ideal for implementing long-distance quantum communications, networking, and information processing by interfacing photons and atoms. Most importantly, our work paves a way for the development of a reliable and efficient genuine triphoton source, thus making the research on multiphoton entanglement within easy reach.