Entanglement distillation for quantum communication network with atomic-ensemble memories

Area of Science:

• Quantum Information Science
• Atomic Physics
• Quantum Communication Networks

Background:

• Atomic ensembles offer long coherence times and collective enhancement for quantum network memory nodes.
• Cavity quantum electrodynamics facilitates nonlinear interactions between atomic ensembles and photons.

Purpose of the Study:

• Investigate entanglement distillation for nonlocal atomic ensembles using photon input-output processes.
• Develop protocols for concentrating and purifying entanglement in atomic ensemble systems.

Main Methods:

• Cavity quantum electrodynamics for photon-atom interactions.
• Entanglement concentration protocols (ECP) for known and unknown pure states.
• Entanglement purification protocols (EPP) for mixed states using parity-check detectors (PCD).

Main Results:

• An optimal ECP was developed for known pure states.
• An efficient ECP was designed for unknown pure states using PCDs.
• An EPP was introduced for mixed entangled states utilizing PCDs.

Conclusions:

• The developed entanglement distillation protocols demonstrate high fidelity and efficiency.
• These protocols are experimentally feasible with current techniques.
• The methods are valuable for advancing quantum communication networks employing atomic-ensemble memories.