Deterministic entanglement-assisted quantum communication over 20 km fiber channel.

Area of Science:

• Quantum Information Science
• Quantum Communication Technologies
• Fiber Optic Communication

Background:

• Entanglement-assisted quantum communication leverages quantum entanglement for enhanced information transfer.
• Current dense coding schemes are largely confined to proof-of-principle experiments.
• Extending quantum communication distances is crucial for practical applications.

Purpose of the Study:

• To experimentally demonstrate deterministic entanglement-assisted quantum communication over long-distance fiber channels.
• To propose and validate a novel continuous-variable (CV) dense coding scheme for improved classical signal transmission.
• To enhance the channel capacity of quantum communication systems.

Main Methods:

• Utilized continuous-variable (CV) entangled states for quantum communication.
• Implemented a new CV dense coding scheme with enhanced classical signals.
• Employed frequency division multiplexing to decode multiple classical signals.
• Transmitted signals through 20.121 km of commercial fiber optic channels.

Main Results:

• Successfully demonstrated deterministic entanglement-assisted quantum communication over 20 km fiber.
• Achieved extended transmission distances for CV entanglement-assisted quantum communication.
• Simultaneously decoded 10 classical signals submerged in shot noise.
• Obtained approximately 3 times the channel capacity compared to classical communication with coherent states.

Conclusions:

• The proposed CV dense coding scheme significantly improves entanglement-assisted quantum communication performance.
• This work represents a critical advancement towards practical, metropolitan-scale entanglement-assisted quantum communication.
• The results pave the way for robust quantum communication networks in real-world scenarios.