Long-lived remote ion-ion entanglement for scalable quantum repeaters

Area of Science:

• Quantum Information Science
• Quantum Communication Networks
• Quantum Metrology

Background:

• Scalable quantum networks require deterministic entanglement distribution over long distances.
• Photon loss in optical fibers limits entanglement distribution efficiency.
• Quantum repeaters with quantum memories are crucial for overcoming distance limitations.

Purpose of the Study:

• To demonstrate robust memory-memory entanglement over 10 km of optical fiber.
• To overcome the decoherence bottleneck in establishing and purifying remote entanglement.
• To advance the development of critical components for quantum repeaters and scalable quantum networks.

Main Methods:

• Development of long-lived trapped-ion quantum memories.
• Implementation of an efficient telecom interface for entanglement distribution.
• Utilizing a high-visibility single-photon entanglement protocol.

Main Results:

• Achieved memory-memory entanglement over 10 km of spooled fiber, surviving beyond the entanglement establishment time.
• Demonstrated a proof-of-principle device-independent quantum key distribution (DI-QKD) over 10 km.
• Reported a positive key rate for DI-QKD over 101 km in the asymptotic limit, exceeding previous work by over two orders of magnitude.

Conclusions:

• The demonstrated memory-memory entanglement is a critical building block for quantum repeaters.
• This work represents a significant advancement toward the realization of scalable quantum networks.
• The developed technologies pave the way for enhanced secure communication and distributed quantum computing.