Broadband fiber-based entangled photon-pair source at telecom O-band

Area of Science:

• Quantum Optics
• Photonics
• Quantum Information Science

Background:

• Entangled photon pairs are fundamental resources for quantum technologies.
• Existing sources often lack sufficient bandwidth for advanced applications.
• Telecom O-band is ideal for long-distance fiber-based quantum communication.

Purpose of the Study:

• To develop a broadband source of polarization-entangled photon pairs.
• To operate in the telecom O-band for practical quantum communication.
• To characterize the entanglement properties and spectral bandwidth.

Main Methods:

• Utilized type-II spontaneous parametric downconversion (SPDC).
• Employed periodically poled silica fiber (PPSF) for efficient nonlinear interaction.
• Measured Hong-Ou-Mandel interference to confirm entanglement and coherence time.
• Quantified entanglement fidelity using quantum state tomography (implied).

Main Results:

• Achieved a record emission bandwidth exceeding 130 nm (∼24 THz) centered at 1306.6 nm.
• Demonstrated a biphoton correlation time of 26.6 fs (FWHM) via Hong-Ou-Mandel interference.
• Obtained high polarization entanglement fidelity (>95.4%) across the entire bandwidth.
• Reported the broadest bandwidth entangled biphotons in the O-band to date.

Conclusions:

• The developed PPSF-based source offers unprecedented bandwidth for O-band entangled photons.
• The high fidelity and broad bandwidth are suitable for advanced quantum communication protocols.
• This source represents a significant advancement for fiber-based quantum information technologies.