A photonic quantum information interface.

Area of Science:

• Quantum Information Science
• Quantum Optics
• Quantum Communication

Background:

• Quantum communication relies on transferring quantum states (qubits) for applications like secure quantum cryptography.
• Photons are ideal carriers for quantum communication, with telecom wavelengths (1,310 nm, 1,550 nm) suited for long distances.
• Alkaline atoms operating around 800 nm are used for quantum information storage and processing, necessitating wavelength conversion interfaces.

Purpose of the Study:

• To demonstrate qubit transfer between photons at distinct wavelengths (1,310 nm and 710 nm).
• To develop interfaces for future quantum networks connecting telecommunication channels and atomic memories.
• To preserve quantum coherence and entanglement during wavelength conversion.

Main Methods:

• Utilized a nonlinear up-conversion process for qubit transfer between photons.
• Employed photons at 1,310 nm and 710 nm for the transfer experiment.
• Investigated two-photon interference between converted and entangled photons.

Main Results:

• Achieved qubit transfer between 1,310 nm and 710 nm photons with over 5% success probability.
• Observed strong two-photon interference between the 710 nm photon and a 1,550 nm photon entangled with the initial 1,310 nm photon.
• Demonstrated high fidelity (over 98%) for the quantum state transfer and entanglement preservation.

Conclusions:

• Successfully demonstrated wavelength conversion for quantum information transfer between different optical domains.
• This method is crucial for integrating telecommunication-based quantum networks with atomic quantum memories.
• The high fidelity and entanglement preservation pave the way for advanced quantum communication and networking applications.