Efficient C-band single-photon upconversion with chip-scale Ti-indiffused pp-LiNbO₃ waveguides

Area of Science:

• Quantum Optics
• Photonics
• Quantum Information Science

Background:

• Single photon frequency upconversion is crucial for quantum networks, enabling compatibility between quantum memories and long-distance communication wavelengths.
• Efficient detection of telecom-wavelength photons is essential for quantum information processing, particularly with silicon-based single-photon detectors.

Purpose of the Study:

• To demonstrate efficient frequency upconversion of single photons at telecom wavelengths.
• To enable the detection of telecom photons using silicon-based single-photon detectors with low dark count rates.
• To improve the performance of quantum nodal networks.

Main Methods:

• Utilized a low-loss titanium-indiffused periodically poled lithium niobate waveguide.
• Employed an erbium-doped fiber amplifier in the L-band as the pump source.
• Implemented a long-wavelength pump configuration and narrow 3.5-GHz bandpass filtering.

Main Results:

• Achieved internal and conversion efficiencies of up to 84.4% and 49.9%, respectively.
• Suppressed dark count rates to 44 kHz.
• Reached 13.9% end-to-end quantum efficiency, including conversion and detection.

Conclusions:

• Demonstrated a viable method for frequency upconversion of single photons at telecom wavelengths.
• The developed technique enhances the compatibility of quantum components in a quantum nodal network.
• The high efficiency and low dark counts pave the way for practical quantum communication and sensing applications.