Entangled Photon Pair Generation in the Telecom O-Band from Nanowire Quantum Dots

Area of Science:

• Quantum optics
• Solid-state physics
• Quantum information science

Background:

• Entangled photon pairs are crucial for quantum communication and computing.
• Telecom O-band offers low loss and dispersion, ideal for long-distance fiber networks.
• Site-controlled nanowire quantum dots are promising for photon generation but limited to visible/NIR-I wavelengths.

Purpose of the Study:

• To demonstrate a bright source of entangled photon pairs in the telecom O-band.
• To establish nanowire quantum dots as a viable platform for telecom-wavelength quantum sources.
• To advance scalable quantum technologies for fiber-based quantum networks.

Main Methods:

• Fabrication and characterization of site-controlled nanowire quantum dots.
• Measurement of fine-structure splitting to assess entanglement potential.
• Quantum-state tomography of the biexciton-exciton cascade to quantify entanglement fidelity and concurrence.

Main Results:

• Demonstrated a bright source of entangled photon pairs in the telecom O-band.
• Measured a fine-structure splitting of 4.6 μeV, suitable for high-fidelity polarization entanglement.
• Achieved a maximum fidelity of 85.8 ± 1.1% to the Φ+ Bell state and 75.1 ± 2.1% concurrence.

Conclusions:

• Site-controlled nanowire quantum dots are viable entangled photon sources at telecom wavelengths.
• This work enables scalable quantum technologies for fiber-based quantum networks.
• The demonstrated source is a significant step towards practical quantum communication systems.