The quantum Internet will support paradigm shifts in cybersecurity, distributed quantum computing, and sensing. Its realization, however, has been held back by the lack of practical technologies to enable deployment and scalability. To date, most demonstrations have been limited to laboratories with expensive resources such as cryogenic and vacuum systems. The authors overcome this challenge by designing a field-deployable quantum memory, based on warm atomic vapor, that demonstrates high-fidelity performance and robustness to environmental noise. This represents a key technology for distributing quantum entanglement across large-scale quantum networks.
The quantum Internet will support paradigm shifts in cybersecurity, distributed quantum computing, and sensing. Its realization, however, has been held back by the lack of practical technologies to enable deployment and scalability. To date, most demonstrations have been limited to laboratories with expensive resources such as cryogenic and vacuum systems. The authors overcome this challenge by designing a field-deployable quantum memory, based on warm atomic vapor, that demonstrates high-fidelity performance and robustness to environmental noise. This represents a key technology for distributing quantum entanglement across large-scale quantum networks.
High-performance quantum memories are a key component for quantum networking infrastructure. Here we demonstrate the first field-deployable, high-fidelity (<95%) memory for photonic polarization qubits based on electromagnetically induced transparency in a warm rubidium vapor. We discuss our work towards optimizing the memory for use in quantum networking applications, specifically to maximize the memory fidelity, efficiency and coherence time. We also describe our engineering efforts in scaling down the size of the memory into a turn-key 2U rackmount device. The module has been designed and tested for use in both academic and industrial settings.
Distributing entanglement over long distances is a core challenge of Quantum Communications. Quantum repeaters, hosting entanglement swapping protocols, have been proposed as a viable solution, though they have yet to be realized commercially. Basic research groups have demonstrated memory-assisted entanglement swapping using NV diamond centers or cold atomic vapor memories. Qunnect is building a product suite to support entanglement swapping based on warm atomic vapor. While the engineering of these systems is challenging, the elimination of extreme cooling and vacuum support provides numerous advantages for network scalability. I will discuss our progress to date and upcoming fiber testbed demonstrations.
Entanglement distribution is a fundamental building block of quantum communication networks, enabling the secure and reliable exchange of quantum information over long distances. Unlike classical communication, quantum networks exploit the unique properties of quantum entanglement to support applications such as quantum key distribution, quantum teleportation, distributed quantum computing, and networked quantum sensing. Although significant progress has been made in recent years, the efficient generation, transmission, and preservation of entangled states remain major research challenges due to photon loss, decoherence, and limitations in current communication infrastructure.This review provides a comprehensive overview of entanglement distribution in quantum communication networks, focusing on the technologies that enable practical implementation and the latest experimental developments. It discusses key approaches for generating and distributing entangled photons through optical fibers, free-space links, and satellite-based communication, together with supporting technologies such as quantum repeaters, quantum memories, and photonic devices. The review also examines recent experimental demonstrations that have advanced long-distance quantum communication while highlighting the technical barriers that must be overcome for large-scale deployment. Finally, emerging applications and future research directions are presented, including the development of scalable quantum networks, the quantum internet, and secure global communication systems. This review aims to provide researchers and students with a clear understanding of the current state of entanglement distribution and its growing role in next-generation quantum communication technologies.
Single photons are the flying qubits of choice for distributing entanglement in a quantum internet. Quantum memories embedded in quantum repeaters are crucial to overcome transmission loss and enhance the rate of quantum communication. A multimode memory can further boost the channel capacity. However, benchmarking and building a practical quantum memory that simultaneously optimizes multiple performance metrics poses two key challenges. Here, we introduce quantum interconnect rate to comprehensively quantify quantum memories, and further demonstrate a high-performance quantum memory that simultaneously integrates three essential criteria at once: large multimode capacity, high efficiency, and high fidelity. Operating on 11-dimensional spatial modes, our memory achieves a uniform efficiency exceeding 80% and qubit storage fidelities above 99%, enabling the efficient storage of high-dimensional qudits. Based on these capabilities, we estimate a distribution of 3.56 bits of quantum information over a 1000-km repeater link in one minute, highlighting a practical pathway toward scalable quantum interconnects and quantum networks.
As quantum computation continues to advance, distributed quantum computing is emerging as a crucial configuration, offering a means to leverage the best technology across diverse platforms. This approach is essential for enhancing scalability and advancing quantum resources towards faulttolerant demonstration. A fundamental element of this design is the establishment of scalable quantum networks with robust quantum memory systems. We have recently demonstrated a high efficiency and high bandwidth solid-state quantum memory developed for the Quantum-Accelerated Internet Testbed (QuAInT) at Oak Ridge National Laboratory (ORNL), reaching28.5±0.2%efficiency and a 630 MHz absorption window in the material. This work for QuAInT represents a collaborative endeavor across multiple institutions to establish the groundwork for a national quantum internet connection. We will highlight that work here, as well as our strategic vision to build a lower temperature and low-latency quantum memory platform.
The Quantum Internet represents a paradigm shift in communication technology, leveraging quantum mechanical principles such as superposition, entanglement, and the no-cloning theorem to enable ultra-secure, high-fidelity, and potentially revolutionary global connectivity. Unlike the classical internet, which transmits bits through electromagnetic signals, the Quantum Internet transmits qubits, allowing the creation of unbreakable cryptographic channels, distributed quantum computation, and quantum-enhanced sensing networks. This paper presents a comprehensive review of the Quantum Internet, covering its underlying principles, layered architecture, enabling hardware technologies, and core communication protocols. We analyze current and emerging applications, from secure government and financial communications to healthcare and fundamental physics experiments. The study highlights the unique advantages of quantum networking, such as intrinsic security against eavesdropping, global-scale entanglement distribution, and integration with distributed computing infrastructures. At the same time, it addresses practical limitations, including distance constraints, quantum memory coherence times, infrastructure costs, and security risks associated with hardware vulnerabilities. Special attention is given to the feasibility of large-scale deployment in India, leveraging national programs such as NM-QTA and QuEST, as well as satellite-based quantum communication initiatives by ISRO. The paper concludes with a roadmap for the realization of a global quantum network, identifying technical, infrastructural, and policy challenges that must be addressed in the coming decades.