On-chip generation of single-photon circularly polarized single-mode vortex beams

Area of Science:

• Quantum optics
• Nanophotonics
• Quantum information science

Background:

• Generating single photons with tailored spin and orbital angular momentum (SAM and OAM) is crucial for high-dimensional quantum systems.
• On-chip generation of single photons with single-mode SAM-OAM states remains a significant challenge.

Purpose of the Study:

• To demonstrate an on-chip method for generating single photons with controlled SAM and OAM.
• To overcome the limitations of current on-chip single-photon sources for quantum applications.

Main Methods:

• Fabrication of anisotropic nanodimers on a substrate to support surface plasmon polariton (SPP) propagation.
• Precise positioning of nanodimers around a quantum emitter (QE) to enable nonradiative QE-SPP coupling.
• Outcoupling of SPPs into free-space propagating radiation with designed SAM and OAM.

Main Results:

• On-chip, room-temperature generation of well-collimated single-mode vortex beams (divergence < 7.5°).
• Generation of circularly polarized photons with high chirality (> 0.97) and different topological charges (l = 0, 1, 2).
• Achieved high single-photon purity with g(2)(0) < 0.15.

Conclusions:

• The developed nanodimer approach enables efficient on-chip generation of single photons with desired SAM and OAM.
• This method can be extended to create multiple, independently polarized single-mode photon channels.
• The technology paves the way for realizing advanced high-dimensional quantum sources for quantum photonic technologies.