Quantum Entanglement Network Enabled by a State-Multiplexing Quantum Light Source.

The rapid development of quantum information science has driven the exploration of advanced quantum light sources capable of generating complex entangled states for large-scale quantum communication and computation. In this work, we demonstrate a state-multiplexing quantum light source that enables the simultaneous generation of multiple entangled photon pairs with distinct temporal modes, paving the way for efficient resource utilization in quantum networks. By integrating this source with superconducting nanowire single-photon detectors (SNSPDs), we achieve high-fidelity entanglement distribution and multiparty quantum communication protocols, showcasing its potential to address key challenges in building a practical quantum internet.

This paper presents a novel approach for creating high-dimensional entangled states using single-photon frequency combs integrated into existing fiber-optic networks. By leveraging the inherent structure of frequency combs, they eliminate the need for nonlinear crystals, simplifying the setup and making it more accessible. The system successfully transmitted entangled states over 50 km of fiber, addressing challenges such as signal loss and noise through the use of superconducting nanowire single-photon detectors (SNSPDs). Applications include quantum key distribution for secure communication and teleportation for transferring quantum states. Challenges remain in effective noise handling, scalability, and practicality in real-world applications. This method represents a significant step in quantum communication by leveraging current infrastructure but requires further advancements in transmission distance, speed, and noise reduction for widespread adoption.

The integration of quantum communication into existing fiber-optic networks is a critical step toward realizing secure and efficient quantum information systems. Current methods often rely on complex setups involving nonlinear crystals, which can be challenging to implement and maintain. This paper introduces an alternative approach using single-photon frequency combs, which offer a simplified and scalable solution for creating high-dimensional entangled states.

Frequency combs are optical sources that emit light at multiple frequencies with precise spacing, enabling the encoding of quantum information across these frequencies. By integrating this technology into fiber-optic networks, we can leverage existing infrastructure to facilitate long-distance quantum communication. The use of superconducting nanowire single-photon detectors (SNSPDs) further enhances the system’s performance by providing high efficiency and low noise characteristics.

The proposed method employs a laser emitting at multiple frequencies, where each tooth of the comb represents a unique quantum state. This setup allows for the efficient encoding of multiple states into a single photon, significantly reducing the complexity of traditional quantum communication systems. The elimination of nonlinear crystals simplifies the system and reduces costs, making it more accessible for widespread deployment.

The system was tested over 50 km of fiber, with SNSPDs used to detect the transmitted photons. These detectors are particularly well-suited for this application due to their high efficiency and low noise characteristics, which are critical for maintaining the integrity of quantum states during transmission. The experimental results demonstrate successful transmission of entangled states over a distance of 50 km using the proposed system. The use of SNSPDs significantly improved detection efficiency and reduced noise levels, enabling reliable communication over long distances. These findings highlight the potential of frequency comb-based systems for quantum communication applications.

While the results are promising, several challenges remain. Effective noise handling is critical for maintaining the integrity of quantum states during transmission, particularly as distances increase. Scalability is another important consideration, as the system must be capable of supporting large-scale networks without compromising performance. Additionally, the practicality of SNSPDs in real-world applications must be addressed, particularly their requirement for cryogenic cooling.

Comparisons with other quantum communication methods reveal trade-offs in terms of speed and information capacity. However, the simplicity and scalability of frequency comb-based systems make them a compelling alternative for long-distance quantum communication.

This paper presents a novel approach for creating high-dimensional entangled states using single-photon frequency combs integrated into fiber-optic networks. The successful transmission of entangled states over 50 km demonstrates the potential of this method for quantum communication applications. While challenges remain in noise handling, scalability, and practicality, the results suggest that frequency comb-based systems could play a significant role in future quantum information networks.