Photonic hybrid state entanglement swapping using cat state superpositions

Area of Science:

• Quantum Information Science
• Quantum Communication
• Quantum Networking

Background:

• Entanglement swapping is crucial for distributing quantum entanglement over long distances.
• Previous protocols often suffer from noise and loss, limiting their practical application.
• Hybrid entanglement, combining discrete and continuous variables, offers potential advantages.

Purpose of the Study:

• To propose and analyze a novel entanglement swapping protocol using hybrid entanglement.
• To assess the protocol's performance under realistic conditions, including photonic loss and measurement imperfections.
• To demonstrate the suitability of the proposed scheme for quantum networking applications.

Main Methods:

• Utilized a hybrid entangled state (Fock state and cat state superposition).
• Modeled photonic loss in propagating continuous variable modes (equal and unequal).
• Employed projective vacuum-one-photon measurement and balanced homodyne detection.
• Investigated homodyne measurement imperfections and success probabilities.

Main Results:

• The proposed entanglement swapping scheme exhibits high fidelity Bell state distribution.
• The protocol demonstrates significant resilience to low levels of photonic loss.
• It shows improved loss resilience compared to schemes using coherent states.
• Success probability was analyzed considering measurement imperfections.

Conclusions:

• The hybrid entanglement swapping protocol is robust against photonic losses.
• It offers a promising solution for distributing entanglement between distant nodes in quantum networks.
• Integration with entanglement purification can further enhance its capabilities for long-distance quantum communication.