Ultrabright polarization-entangled photon pair source for frequency-multiplexed quantum communication in free-space

Area of Science:

• Quantum communication
• Quantum networking
• Free-space optics

Background:

• Satellite quantum networks require efficient entangled photon sources to overcome high channel loss.
• Current sources face limitations with detector bandwidth and space-readiness.

Purpose of the Study:

• To report an ultrabright entangled photon source optimized for long-distance free-space transmission.
• To address limitations in current single photon detector technology for satellite downlinks.

Main Methods:

• Developed an ultrabright entangled photon source operating in a specific wavelength range.
• Utilized spectral correlations from hyper-entanglement in polarization and frequency for demultiplexing.
• Employed wavelength demultiplexing to match photon flux with detector bandwidth.

Main Results:

• Achieved pair emission rates exceeding detector bandwidth.
• Demonstrated efficient demultiplexing using spectral correlations.
• Source is optimized for detection with space-ready single photon avalanche diodes (Si-SPADs).

Conclusions:

• The developed source is crucial for overcoming channel loss in satellite quantum communication.
• This technology paves the way for broadband, long-distance entanglement distribution via satellites.
• Advances in source technology are essential for practical quantum network expansion.