Tailored photon-pair generation in optical fibers.

Area of Science:

• Quantum optics
• Photonics
• Materials science

Background:

• Spontaneous four-wave mixing (SFWM) in optical fibers is a key source for quantum information applications.
• Controlling the spectral properties of photon pairs from SFWM is crucial for generating pure single photons.
• Existing methods often require spectral filtering, reducing efficiency and photon purity.

Purpose of the Study:

• To experimentally control the spectral structure of photon pairs generated via SFWM.
• To demonstrate direct heralding of single photons in pure-state wave packets without spectral filtering.
• To investigate the role of fiber dispersion in manipulating photon pair properties.

Main Methods:

• Fabrication of microstructured optical fibers with designed dispersion profiles.
• Generation of photon pairs using spontaneous four-wave mixing in these fibers.
• Characterization of the spectral properties and correlations of the generated photon pairs.

Main Results:

• Achieved experimental control over photon pair wavelengths and joint spectral structure.
• Produced photon pairs with no spectral correlations, enabling direct single-photon heralding.
• Demonstrated an experimental purity of (85.9+/-1.6)% for heralded single photons.
• Theoretical analysis indicates a potential purity of 94.5% with optimized fiber length.

Conclusions:

• Designed dispersion in microstructured fibers allows precise manipulation of SFWM photon pair properties.
• Direct heralding of pure-state single photons is achievable without spectral filtering.
• This technique offers a promising route for efficient generation of high-purity photons for quantum technologies.