Spin angular momentum-encoded single-photon emitters in a chiral nanoparticle-coupled WSe₂ monolayer

Area of Science:

• Quantum Optics
• Nanophotonics
• Materials Science

Background:

• Spin angular momentum (SAM)-encoded single-photon emitters, or circularly polarized single photons, are crucial for chiral quantum optics and cryptography.
• Generating these photons from subwavelength nanostructures without magnetic fields remains a significant challenge.

Purpose of the Study:

• To demonstrate a method for generating SAM-encoded single-photon emitters using strained WSe2 monolayers coupled with chiral plasmonic gold nanoparticles.
• To investigate the properties of single-photon emission from these nanostructures.

Main Methods:

• Coupling a strained WSe2 monolayer with chiral plasmonic gold nanoparticles.
• Observing and analyzing single-photon emission properties, including photon antibunching and circular polarization characteristics.
• Utilizing Stokes parameters to quantify circular polarization.

Main Results:

• Single-photon emissions were successfully observed at the nanoparticle locations.
• Photon antibunching behavior with a g(2)(0) value of approximately 0.3 indicated single-photon emission.
• Strong circular polarization properties were confirmed, with a slight preference for left-circular polarization.
• Comparison with achiral gold nanocubes highlighted the importance of chirality.

Conclusions:

• The study successfully demonstrates SAM-encoded single-photon emitters using a novel nanostructure without external magnetic fields.
• This approach offers insights into the interaction between plasmonic dipoles and single photons.
• The findings facilitate the development of advanced chiral quantum optics and related technologies.