Polarization insensitive frequency conversion for an atom-photon entanglement distribution via a telecom network

Area of Science:

• Quantum communication
• Quantum information science
• Atomic physics

Background:

• Long-distance quantum communication relies on quantum storages compatible with telecom photons.
• Atomic quantum storages offer long storage times but lack direct telecom photon interfacing.
• A wavelength mismatch exists between telecom photons and atomic ensembles.

Purpose of the Study:

• To demonstrate a polarization-insensitive solid-state quantum frequency conversion.
• To bridge the wavelength gap between short-wavelength photons entangled with atomic ensembles and the telecom range.
• To enable interfacing atomic quantum storages with telecom photonic infrastructure.

Main Methods:

• Generated atom-photon entanglement using a Rubidium (Rb) atomic ensemble.
• Employed a nonlinear-crystal-based frequency converter within a Sagnac interferometer.
• Translated the wavelength of entangled photons to the telecom range.

Main Results:

• Successfully demonstrated polarization-insensitive quantum frequency conversion.
• Maintained entanglement between the photon and the atomic ensemble after wavelength conversion.
• Achieved conversion of short-wavelength photons to the telecom range.

Conclusions:

• Solid-state quantum frequency conversion is a viable method to interface atomic quantum storages with telecom photons.
• This technique overcomes a critical obstacle for realizing long-distance quantum communication.
• The demonstrated method preserves quantum entanglement during wavelength translation.