High-dimensional quantum key distribution with focused structured photons

Area of Science:

• Quantum Information Science
• Free-Space Quantum Communication
• Optical Physics

Background:

• High-dimensional quantum key distribution (HD-QKD) offers superior key rates and noise resilience compared to qubit-based QKD.
• Orbital angular momentum states of structured photons are a key method for HD-QKD implementation.
• Free-space QKD faces challenges including diffraction, limited aperture size, and atmospheric turbulence.

Purpose of the Study:

• To address practical limitations in free-space HD-QKD using focused, structured photons.
• To enhance transmission efficiency, turbulence robustness, and achievable key rates.
• To enable higher-dimensional encoding and superior performance with smaller receiving apertures.

Main Methods:

• Implementation of HD-QKD using focused, structured photons.
• Numerical simulations to evaluate transmission efficiency and turbulence robustness.
• Analysis of performance metrics including key rates and transmission distances.

Main Results:

• Focused, structured photons significantly enhance transmission efficiency and turbulence resilience in free-space HD-QKD.
• The proposed method leads to higher key rates and extended transmission distances.
• Higher-dimensional QKD is enabled, achieving superior performance with smaller receiving apertures.

Conclusions:

• Focused, structured photons offer a robust solution for free-space HD-QKD, overcoming key practical challenges.
• The approach is particularly suitable for mobile platforms like UAVs and satellites.
• This work advances the development of robust structured photon-based QKD for quantum networks.