The distribution of secret keys with information-theoretic security, made possible by the laws of quantum mechanics, is undoubtedly one of the main achievements of quantum information processing and communications. In recent years, quantum key distribution (QKD) has been implemented in real-world conditions and commercial systems are now available. Despite this progress, however, QKD remains a relatively difficult to operate and costly technology, hindering its widespread use for high-security applications. The photonic integration of QKD devices can play a crucial role in this direction by reducing their size and cost by several orders of magnitude.
The distribution of secret keys with information-theoretic security, made possible by the laws of quantum mechanics, is undoubtedly one of the main achievements of quantum information processing and communications. In recent years, quantum key distribution (QKD) has been implemented in real-world conditions and commercial systems are now available. Despite this progress, however, QKD remains a relatively difficult to operate and costly technology, hindering its widespread use for high-security applications. The photonic integration of QKD devices can play a crucial role in this direction by reducing their size and cost by several orders of magnitude.
Quantum key distribution (QKD) enables secure secret key exchange with information-theoretic security by leveraging the principles of quantum mechanics. Continuous-variable QKD (CV-QKD), which utilizes coherent states and coherent detection, has gained attention as a promising approach due to its seamless integration with existing telecommunications networks. CV-QKD systems, which are built with standard telecommunication components, open the door—through photonic integration technology—to the development of devices that are more affordable, compact, and energy efficient. This paper reviews the current state of the art and highlights our recent progress toward fully integrated CV-QKD systems.
Quantum key distribution (QKD) is a quantum communication technology that offers absolute security. Among its various implementations, continuous-variable (CV) QKD has garnered significant attention due to its high secret key generation rates and compatibility with conventional optical telecommunication infrastructure, which operates under ambient conditions. However, chip-based integration is crucial for realizing practical and scalable CV-QKD networks, and photonic integrated circuit technology is a potential solution, leveraging the on-chip integration of essential optical components onto silicon photonic circuits. Therefore, this work presents a compact, stable, and cost-effective quantum photonic CV-QKD system on a chip. Our architecture combines time- and polarization-multiplexing with high-extinction-ratio pulse generation to mitigate excess noise. At the same time, a real-time feedback control mechanism compensates for polarization drift, ensuring robust system performance. Fiber-based evaluations reveal secret key generation rates of 2.55 Mbps over 25 km and 0.737 Mbps over 50 km with 12 h stable operation, establishing, to our knowledge, a new benchmark for integrated photonic CV-QKD systems with both the transmitter and receiver on-chip. These results mark a significant milestone in on-chip quantum communication, paving the way for widespread adoption of photonic integrated circuits in future metropolitan quantum-secure networks.
The ability to distribute secret keys between two parties with information-theoretic security, that is regardless of the capacities of a malevolent eavesdropper, is one of the most celebrated results in the field of quantum information processing and communication. Indeed, quantum key distribution illustrates the power of encoding information on the quantum properties of light and has far-reaching implications in high-security applications. Today, quantum key distribution systems operate in real-world conditions and are commercially available. As with most quantum information protocols, quantum key distribution was first designed for qubits, the individual quanta of information. However, the use of quantum continuous variables for this task presents important advantages with respect to qubit-based protocols, in particular from a practical point of view, since it allows for simple implementations that require only standard telecommunication technology. In this review article, we describe the principle of continuous-variable quantum key distribution, focusing in particular on protocols based on coherent states. We discuss the security of these protocols and report on the state-of-the-art in experimental implementations, including the issue of side-channel attacks. We conclude with promising perspectives in this research field.
Continuing efforts have been made to develop practical quantum key distribution (QKD) systems on the installed fiber networks since early 2000s [1]. Recently, several groups have demonstrated high-speed QKD systems [2,3] with GHz-clock frequency working stably on the installed-fiber networks [4-7]. Along with the hardware development, an efficient key management protocol [7] has been implemented to construct a QKD platform to supply information-theoretically secure key for multiple applications. The highly available QKD platform is expected to promote social deployment of the QKD technology.
The ability to distribute secret keys between two parties with information-theoretic security, that is, regardless of the capacities of a malevolent eavesdropper, is one of the most celebrated results in the field of quantum information processing and communication. Indeed, quantum key distribution illustrates the power of encoding information on the quantum properties of light and has far reaching implications in high-security applications. Today, quantum key distribution systems operate in real-world conditions and are commercially available. As with most quantum information protocols, quantum key distribution was first designed for qubits, the individual quanta of information. However, the use of quantum continuous variables for this task presents important advantages with respect to qubit based protocols, in particular from a practical point of view, since it allows for simple implementations that require only standard telecommunication technology. In this review article, we describe the principle of continuous-variable quantum key distribution, focusing in particular on protocols based on coherent states. We discuss the security of these protocols and report on the state-of-the-art in experimental implementations, including the issue of side-channel attacks. We conclude with promising perspectives in this research field.
Quantum communications enable the transmission of information in a secure way that is ensured by the laws of quantum physics. Current quantum-safe communication systems are based on quantum key distribution (QKD) technology at their core. In the most recent years, a remarkable effort has been put into practical implementations of QKD with a focus on their integration into classical optical networks, some of which are becoming commercially available. However, even with the ongoing development of QKD systems, there are efforts toward their miniaturization, power efficiency improvement, and enhancement of their flexibility and functionality.In this paper, we outline major QKD protocols and review recent advances in QKD systems based on photonic integrated circuits. Finally, we will discuss the potential feasibility of multi-protocol QKD chips leveraging the advantages of different protocols in one solution.