Heralded quantum steering over a high-loss channel

Area of Science:

• Quantum Information Science
• Quantum Communication
• Quantum Optics

Background:

• Entanglement is crucial for quantum information tasks like secure communication.
• Verifying entanglement over long distances is challenging due to signal loss in optical fibers or free-space channels.
• This loss creates a detection loophole, hindering reliable entanglement verification.

Purpose of the Study:

• To design and experimentally demonstrate a scheme for verifying quantum entanglement in high-loss scenarios.
• To overcome the technological limitations of long-distance entanglement verification.
• To enable device-independent quantum communication and the development of quantum repeaters.

Main Methods:

• Developed a novel scheme utilizing entanglement swapping.
• Employed entanglement swapping to herald photons after traversing a lossy channel.
• Implemented quantum steering in an event-ready manner.

Main Results:

• Successfully verified entanglement with at least 14.8 ± 0.1 dB of added loss.
• This loss is equivalent to approximately 80 km of standard telecommunication fiber.
• Demonstrated the feasibility of entanglement verification under realistic high-loss conditions.

Conclusions:

• The developed scheme overcomes a key barrier in device-independent communication.
• This breakthrough facilitates quantum communication and quantum repeater realization in high-loss environments.
• The results pave the way for robust, long-distance quantum information processing.