Integrated, bright broadband, two-colour parametric down-conversion source

Area of Science:

• Quantum optics
• Integrated photonics
• Nonlinear optics

Background:

• Broadband quantum light is essential for quantum metrology and spectroscopy.
• Entangled two-photon absorption requires high photon flux and time-frequency entanglement.
• Traditional spontaneous parametric down-conversion (SPDC) sources have limitations in wavelength and photon splitting.

Purpose of the Study:

• To demonstrate a novel integrated two-colour SPDC source.
• To achieve high brightness and broad bandwidth for quantum applications.
• To generate strong time-frequency entanglement in photon pairs.

Main Methods:

• Utilized a group-velocity matched lithium niobate waveguide.
• Employed continuous wave (CW) laser light for pumping.
• Converted narrow-band pump light to broadband pulses.

Main Results:

• Achieved exceptional brightness (1.52 × 10^6 pairs/mW/GHz) and large bandwidth (7.8 THz FWHM).
• Generated photon pairs with short correlation times (~120 fs).
• Maintained narrow pump bandwidth (<1 MHz), yielding strong time-frequency entanglement.

Conclusions:

• The integrated source provides a powerful resource for quantum metrology and spectroscopy.
• The demonstrated technology overcomes limitations of bulk-crystal SPDC.
• The source is adaptable to various central wavelengths and offers high performance.