On-chip Quantum Interference of Indistinguishable Single Photons from Integrated Independent Molecules
Experiments on a quantum photonic chip have demonstrated on-chip Hong–Ou–Mandel quantum interference of indistinguishable single photons, achieving visibilities above 0.97 for two molecules coupled individually to two waveguides. Integrating independent channels of indistinguishable single photons on-chip is essential for scalable optical quantum information processing.
Challenges in Single-Photon Emitters
This process requires separate solid-state single-photon emitters to have identical lifetime-limited transitions, a difficult goal due to spectral diffusion caused by complex charge noise near surfaces affected by nanofabrication techniques.
Molecular Quantum Photonic Chip Development
In this work, a molecular quantum photonic chip was developed by embedding molecules in a single-crystalline organic nanosheet integrated with single-mode waveguides without nanofabrication, ensuring stable lifetime-limited transitions.
- Using Stark tuning, 100 waveguide-coupled molecules were precisely tuned to the same frequency.
- On-chip Hong–Ou–Mandel interference visibilities exceeded 0.97 for two molecules coupled to separate waveguides.
Quantum Beating and Single-Photon Properties
For two molecules with a controlled frequency difference, we unveiled over 100-µs-long quantum beating in the interference, showing both excellent single-photon purity (particle nature) and long coherence (wave nature) of the emission.
This reveals both high single-photon purity and long coherence times, highlighting the quality of the emission from these molecules.
Author's Summary
This study demonstrates high-visibility quantum interference of indistinguishable single photons from independent molecules integrated on a chip, overcoming common fabrication challenges through a novel molecular nanosheet approach.