High-brightness single photon source from a quantum dot in a directional-emission nanocavity

Area of Science:

• Quantum optics
• Solid-state physics
• Nanophotonics

Background:

• Single photon sources are crucial for quantum technologies.
• Efficient light extraction from quantum emitters is a key challenge.
• Photonic crystal cavities offer a promising solution for enhancing light-matter interactions.

Purpose of the Study:

• To analyze a single photon source based on an Indium Arsenide (InAs) quantum dot coupled to a directional-emission photonic crystal (PC) cavity.
• To improve light collection and coupling efficiency for single photon emission.
• To investigate the potential for local optical excitation using cavity modes.

Main Methods:

• Fabrication of a perturbed photonic crystal cavity in Gallium Arsenide (GaAs).
• Coupling of an InAs quantum dot to the PC cavity.
• Measurement of quantum dot lifetime, collection efficiency, and fiber coupling efficiency.
• Characterization of photon antibunching using second-order correlation measurements (g((2))(0)).

Main Results:

• Reduced quantum dot lifetime to 45 ps (over 10x improvement).
• Improved collection efficiency into an objective lens (NA = 0.75) by a factor of 4.5.
• Enhanced coupling efficiency into a single mode fiber by a factor of 1.9.
• Achieved strong photon antibunching (g((2))(0) = 0.05), confirming single photon emission.
• Demonstrated efficient coupling to a higher-order cavity mode.

Conclusions:

• The perturbed PC cavity design significantly enhances the performance of InAs quantum dot single photon sources.
• This improved efficiency is critical for advancing quantum communication and computation.
• The cavity design offers versatile functionalities, including efficient light collection and local optical excitation.