Quantum communication leverages the physical properties of entanglement and superposition to create networks capable of connecting quantum computers, sensors, and secure nodes. Photons are a particularly viable information vehicle as they are unaffected by a broad range of environmental variables. They are also very versatile, supporting the teleportation of quantum information upon interacting with information-carrying qubits, whether these qubits are generated by a quantum computer or a random qubit source. Existing and emerging technologies will be discussed, as well as perspectives on the open challenges of the field.
Quantum communication leverages the physical properties of entanglement and superposition to create networks capable of connecting quantum computers, sensors, and secure nodes. Photons are a particularly viable information vehicle as they are unaffected by a broad range of environmental variables. They are also very versatile, supporting the teleportation of quantum information upon interacting with information-carrying qubits, whether these qubits are generated by a quantum computer or a random qubit source. Existing and emerging technologies will be discussed, as well as perspectives on the open challenges of the field.
Recent progress in quantum technologies has brought quantum communication and networking from a largely theoretical idea to an emerging practical reality. By exploiting fundamental quantum phenomena such as superposition and entanglement, quantum communication promises capabilities that are fundamentally different and out of reach for classical communication systems, particularly in terms of security and information sharing. This review aims to present the essential theoretical concepts required to understand quantum communication, alongside an experimental and engineering perspective that highlights how these ideas are realized using real hardware. We explain core principles and protocols in a manner that connects the physics to practical system design, allowing readers to see how quantum theory and communication technology jointly enable quantum networking. The paper further surveys recent experimental and technological advances that have made practical quantum communication possible, emphasizing the role of photonic hardware, sources, detectors, and integrated platforms in enabling key operations, now leading to deployment of multi-node long-distance quantum networks. Finally, we also present the current developments in quantum-secure communication and quantum networking efforts undergoing in India, placing them in the context of the global progress.
Quantum communication represents a revolutionary advancement over classical information theory, which leverages unique quantum mechanics properties like entanglement to achieve unprecedented capabilities in secure and efficient information transmission. Unlike bits in classical communication, quantum communication utilizes qubits in superposition states, allowing for novel information storage and processing. Entanglement, a key quantum phenomenon, enables advanced protocols with enhanced security and processing power. This paper provides a comprehensive overview of quantum communication, emphasizing the role of entanglement in theoretical foundations, practical protocols, experimental progress, and security implications. It contrasts quantum communications potential applications with classical networks, identifying areas where entanglement offers significant advantages. The paper explores the fundamentals of quantum mechanics in communication, the physical realization of quantum information, and the formation of secure quantum networks through entanglement-based strategies like Quantum Key Distribution (QKD) and teleportation. It addresses the challenges of long-distance quantum communication, the role of quantum repeaters in scaling networks, and the conceptualization of interconnected quantum networks. Additionally, it discusses strides towards the Quantum Internet, Quantum Error-Correcting codes, and quantum cryptographys role in ensuring secure communication. By highlighting the role of entanglement, this paper aims to inspire further research and innovation in secure and efficient information exchange within quantum networks.
With the recent advancements and developments in quantum technologies, the emerging field of quantum communication and networking has gained the attention of the researchers. Owing to the unique properties of quantum mechanics, viz., quantum superposition and entanglement, this new area of quantum communication has shown potential to replace modernday communication technologies. The enhanced security and high information sharing ability using principles of quantum mechanics has encouraged networking engineers and physicists to develop this technology for next generation wireless systems. However, a conceptual bridge between the fundamentals of quantum mechanics, photonics and the deployability of a quantum communication infrastructure is not well founded in the current literature. This paper aims to fill this gap by merging the theoretical concepts from quantum physics to the engineering and computing perspectives of quantum technology. This paper builds the fundamental concepts required for understanding quantum communication, reviews the key concepts and demonstrates how these concepts can be leveraged for accomplishing successful communication. The paper delves into implementation advancements for executing quantum communication protocols, explaining how hardware implementation enables the achievement of all basic quantum computing operations. Finally, the paper provides a comprehensive and critical review of the state-of-the-art advancements in the field of quantum communication and quantum internet; and points out the recent trends, challenges and open problems for the real-world realization of next generation networking systems.
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.
The impact of quantum technology will be profound and far-reaching: secure communication networks for consumers, corporations and government; precision sensors for biomedical technology and environmental monitoring; quantum simulators for the design of new materials, pharmaceuticals and clean energy devices; and ultra-powerful quantum computers for addressing otherwise impossibly large datasets for machine learning and artificial intelligence applications. However, engineering quantum systems and controlling them is an immense technological challenge: they are inherently fragile; and information extracted from a quantum system necessarily disturbs the system itself. Of the various approaches to quantum technologies, photons are particularly appealing for their low-noise properties and ease of manipulation at the single qubit level. We have developed an integrated waveguide approach to photonic quantum circuits for high performance, miniaturization and scalability. We will described our latest progress in generating, manipulating and interacting single photons in waveguide circuits on silicon chips.
Quantum entanglement and teleportation are the key resources building the backbone of quantum technologies, such quantum communications, quantum networks, and quantum computations. The quantum communication networks are based on long-range distribution of entangled photons and teleportation of photon qubit states. The resource efficient measurement-based quantum computing models relies on cluster entangled states and the teleportation of logical operations between qubit sites. Silicon photonics provides a versatile platform for quantum information processing on chip, thanks to the CMOS-compatible fabrication process, ability to integrate thousands of components, and precise manipulation of quantum states on a single chip. Here we show our recent work on quantum entanglement and quantum teleportation technology based our advanced silicon photonics platform, a significant step towards future quantum network and optical quantum computing.