Ultra-high-rate nonclassical light source with 50 GHz-repetition-rate mode-locked pump pulses and multiplexed...

Area of Science:

• Quantum Information Science
• Quantum Optics
• Photonics

Background:

• Heralded single photons (HSPs) and entangled photon pairs (EPPs) are crucial for quantum information technologies.
• Spontaneous parametric down-conversion (SPDC) is a key source for these quantum states.
• Existing sources often face limitations in generation rate and efficiency.

Purpose of the Study:

• To develop a novel ultra-high-rate nonclassical light source.
• To demonstrate its capability for generating both HSPs and EPPs.
• To enable scalable quantum-photonic experiments.

Main Methods:

• Utilizing 50 GHz-repetition-rate mode-locked pump pulses.
• Employing multiplexed superconducting nanowire single-photon detectors.
• Characterizing single-photon states via second-order intensity correlation (g(2)).
• Performing polarization-entangled photon pair experiments.

Main Results:

• Achieved a heralding rate exceeding 20 Mcps with g(2) < 1/2, confirming single-photon states.
• Observed nonclassicality (g(2) < 1) even at rates above 50 Mcps.
• Obtained a maximum coincidence rate of 1.6 Mcps for EPPs with a fidelity of 0.881 ± 0.000254.

Conclusions:

• The developed source offers unprecedented generation rates for nonclassical light.
• It is versatile, supporting both heralded single photons and entangled photon pairs.
• This technology is promising for large-scale quantum-photonic experiments facing low success probabilities or high attenuation.