Cavity-enhanced and temporally multiplexed atom-photon entanglement interface

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Optics

Background:

• Quantum repeaters are essential for long-distance quantum communication but require efficient quantum memories.
• Existing quantum memory technologies face challenges in retrieval efficiency, storage capacity, and lifetime.

Purpose of the Study:

• To develop and demonstrate a high-retrieval-efficiency, temporally multiplexed atom-photon entanglement source.
• To improve the generation probability of atom-photon entanglement for practical quantum repeater applications.

Main Methods:

• Utilized a cold atomic ensemble and a train of 12 temporally multiplexed write pulses to generate entangled photon-spin wave pairs.
• Employed a polarization interferometer to encode photonic qubits across 12 temporal modes.
• Integrated a ring cavity to enhance retrieval efficiency from the stored spin-wave qubits.

Main Results:

• Achieved an intrinsic retrieval efficiency of 70.4% for spin-wave qubits.
• Demonstrated a ~12.1-fold increase in atom-photon entanglement generation probability compared to single-mode sources.
• Measured a Bell parameter of 2.21(2) and a memory lifetime up to ~125 µs.

Conclusions:

• The developed temporally multiplexed source significantly enhances atom-photon entanglement generation.
• This technology represents a key advancement towards practical quantum repeaters with improved performance.
• The high retrieval efficiency and long memory lifetime are critical for scalable quantum communication networks.