Enhancements to quantum communication performance utilizing a prototype photonic lantern and multiplexed...

Area of Science:

• Quantum communication
• Optical physics
• Photonics engineering

Background:

• Effective optical interfacing is crucial for free-space quantum key distribution (QKD) receiver performance.
• Direct coupling to single-photon detectors (SPDs) presents engineering difficulties.
• Single-mode fibers necessitate complex adaptive optics for free-space links.

Purpose of the Study:

• To address the bandwidth limitations of multimode fibers (MMFs) in free-space QKD systems.
• To demonstrate a novel photonic lantern for improved optical coupling.
• To maintain the advantages of MMF coupling while mitigating bandwidth constraints.

Main Methods:

• Development of a prototype photonic lantern.
• Integration of the photonic lantern with a free-space quantum channel and SPDs.
• Characterization of optical coupling efficiency and bandwidth performance.

Main Results:

• The photonic lantern successfully couples light from a free-space channel into multiple, less multimodal fibers.
• The proposed system retains the benefits of large MMF coupling.
• Bandwidth limitations typically associated with larger core MMFs are significantly reduced.

Conclusions:

• The photonic lantern offers a viable solution for enhancing optical interfacing in free-space QKD.
• This technology mitigates engineering challenges and reduces the need for adaptive optics.
• The demonstrated prototype shows potential for improving the performance and practicality of QKD receivers.