Broadband polarization-entangled source for C+L-band flex-grid quantum networks

Area of Science:

• Quantum Information Science
• Optical Communications
• Quantum Networking

Background:

• Growing demand for optical network capacity drives interest in expanding beyond the C-band.
• The L-band remains underutilized in quantum networking despite its potential for increased capacity.

Purpose of the Study:

• To demonstrate an ultrabroadband two-photon source for quantum networking applications.
• To enable spectral control and allocation across both C- and L-bands within a single setup.

Main Methods:

• Integration of wavelength-selective switches for C- and L-band control.
• Development of an ultrabroadband two-photon source.
• Polarization state tomography for channel characterization.

Main Results:

• Complete spectral routing and allocation across 7.5 THz demonstrated.
• Average fidelity of 0.98 achieved across 150 pairs of 25-GHz channels.
• Total distillable entanglement exceeding 181 kbits/s.

Conclusions:

• The demonstrated source facilitates optimal entanglement resource utilization across the full C+L-band.
• This technology is designed for flex-grid optical networks, enhancing quantum communication capabilities.