Quantum frequency conversion using 4-port fiber-pigtailed PPLN module

Area of Science:

• Quantum Optics
• Quantum Information Science
• Photonics

Background:

• Quantum frequency conversion (QFC) is crucial for quantum interconnects, especially within telecom photonic networks.
• Compact, fiber-coupled QFC modules are essential for practical quantum applications.

Purpose of the Study:

• To develop and demonstrate a compact, fiber-coupled quantum frequency conversion module.
• To enable efficient wavelength shifting of single photons for quantum networking.

Main Methods:

• Utilized a fiber-coupled 4-port frequency converter based on a periodically poled lithium niobate (PPLN) waveguide.
• Employed spontaneous parametric down-conversion (SPDC) to generate and detect heralded single photons.
• Measured cross-correlation functions to verify quantum properties before and after QFC.

Main Results:

• Successfully shifted a single photon's wavelength from 780 nm to 1541 nm with high fidelity.
• Achieved a high cross-correlation function of 40.45 ± 0.09 for heralded photons.
• Demonstrated a nonclassical cross-correlation value of 13.7 ± 0.4 after QFC, preserving quantum statistics.
• Attained a maximum device efficiency of 0.73.

Conclusions:

• The developed QFC module is compact, fiber-closed, and highly efficient.
• This technology facilitates the interfacing of atomic quantum systems with fiber-optic communication networks.
• The preserved quantum statistical properties are vital for advanced quantum communication protocols.