Fiber-based frequency-degenerate polarization entangled photon pair sources for information encoding

Area of Science:

• Quantum Optics
• Quantum Information Science
• Photonics

Background:

• Entangled photon pairs are crucial for quantum communication and computation.
• Previous methods often face limitations in spectral properties or generation efficiency.

Purpose of the Study:

• To propose and experimentally demonstrate a novel scheme for generating frequency-degenerate polarization entangled photon pairs in the telecom band.
• To enable efficient quantum information encoding via polarization entanglement.

Main Methods:

• Utilizing vector spontaneous four-wave mixing (SFWM) within a Sagnac fiber loop.
• Exploiting quantum interference of clockwise and counter-clockwise biphoton states at a 50:50 coupler.
• Performing Bell state measurements to verify entanglement quality.

Main Results:

• Achieved high raw fringe visibilities of 91% and 90% for two-photon interference under non-orthogonal polarization bases.
• Demonstrated a simplified Bell state measurement with a fringe visibility of 83%.
• Successfully generated frequency-degenerate polarization entangled photon pairs in the telecom band.

Conclusions:

• The proposed scheme provides a robust method for generating high-quality entangled photon pairs.
• The frequency-degenerate property is essential for encoding quantum information using Bell states.
• This work contributes to advancements in quantum communication technologies.