Quantum Technology: Driving Commercialisation of an Enabling Science
Engineering quantum secure communication systems with photonic integrated circuits
Taofiq K. Paraïso, Thomas Roger, Davide G. Marangon, Innocenzo De Marco, Mirko Sanzaro, Robert Woodward, J. F. Dynes, Zhiliang L. Yuan, Andrew J. Shields
Quantum key distribution (QKD) offers the highest possible levels of communication secrecy. Using the laws of quantum mechanics, QKD protocols allow two distant parties to establish symmetric encryption keys that can be proven information theoretically secure. In order to make this technology accessible to a wide range of sectors, it is essential to address the questions of cost, volume production and compatibility with standard Telecom/Datacom infrastructures. While over the last few years, a number of works were devoted to the demonstration of photonic integrated circuits for quantum communications, a practical solution to interface these chips in a complete system remained an elusive goal. We review our efforts in integrating the core optical functions of quantum key distribution onto quantum photonic chips and in demonstrating the first standalone photonic integrated QKD system. Our approach tackles various system integration challenges related to packaging, optoelectronic design and power consumption. The quantum hardware is assembled in pluggable interconnects that guarantee efficient thermal management and forward compatibility of a same host electronics with successive generations of chips. Autonomous operation and long-term stability are demonstrated in realistic operation conditions. Our work offers new pathways for practical implementations of QKD and its viable deployment at large scales.
Quantum key distribution (QKD) offers the highest possible levels of communication secrecy. Using the laws of quantum mechanics, QKD protocols allow two distant parties to establish symmetric encryption keys that can be proven information theoretically secure. In order to make this technology accessible to a wide range of sectors, it is essential to address the questions of cost, volume production and compatibility with standard Telecom/Datacom infrastructures. While over the last few years, a number of works were devoted to the demonstration of photonic integrated circuits for quantum communications, a practical solution to interface these chips in a complete system remained an elusive goal. We review our efforts in integrating the core optical functions of quantum key distribution onto quantum photonic chips and in demonstrating the first standalone photonic integrated QKD system. Our approach tackles various system integration challenges related to packaging, optoelectronic design and power consumption. The quantum hardware is assembled in pluggable interconnects that guarantee efficient thermal management and forward compatibility of a same host electronics with successive generations of chips. Autonomous operation and long-term stability are demonstrated in realistic operation conditions. Our work offers new pathways for practical implementations of QKD and its viable deployment at large scales.
We review our efforts in integrating optical hardware for quantum key distribution onto photonic chips and in engineering the first standalone photonic integrated QKD system. Our approach tackles various system integration challenges related to packaging, optoelectronic design and power consumption. The quantum hardware is assembled in pluggable interconnects that guarantee efficient thermal management and forward compatibility of a same host electronics with successive generations of chips. Autonomous operation and long-term stability are demonstrated in realistic operation conditions. Our work offers new pathways for practical implementations of QKD and its viable deployment at large scales.
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.
Quantum communication promises unconditional security by leveraging the fundamental laws of quantum physics, which make eavesdropping detectable through the disturbance it introduces in quantum states. A cornerstone of this technology is quantum key distribution (QKD), enabling the distribution of a shared secret key between distant users with information- theoretic security, rather than relying on assumptions about an eavesdropper’s computational power, as in classical cryptography. However, current QKD systems rely largely on bulk-optical solutions, which limits scalability, stability, and integration into existing telecommunication infrastructures. Photonic integrated circuits (PICs) offer a promising platform to overcome these challenges by providing compact, stable, and CMOS-compatible architectures. This PhD work investigates integrated photonic platforms for practical quantum communication at telecommunication wavelengths, with a focus on demonstrating QKD protocols across three different encoding schemes: time-bin, frequency-bin, and path. First, a time-bin QKD receiver using a borosilicate-glass integrated imbalanced Mach–Zehnder interferometer (iMZI) is developed and compared with a fiber-based receiver, showing enhanced phase stability and improved long-distance secure key rates. Next, frequency-bin entanglement-based QKD is implemented using silicon microring resonators, demonstrating high-visibility quantum interference and active phase-stabilization techniques. Finally, a chip-to-chip path-entangled QKD link is realized using silicon photonic spiral sources, representing a crucial step toward fully integrated quantum transceivers. Across these experiments, this PhD thesis establishes a unified experimental framework for integrated QKD and evaluates performance in terms of quantum bit error rate, secure key rate, and system stability under realistic operating conditions. Together, the results provide a proof-of-concept demonstration of scalable, high-performance quantum communication using PIC technology, advancing toward practical deployment in future quantum networks and laying foundations for multidimensional and fully integrated quantum communication nodes.
Quantum key distribution (QKD) is moving from laboratory demonstrations toward network deployment, and integrated photonic chips provide a hardware route for compact, stable and scalable systems. This review summarizes progress in integrated photonic chips for QKD from protocol requirements to deployable systems. It first examines how decoy-state BB84, measurement-device-independent QKD (MDI-QKD), twin-field QKD (TF-QKD), continuous-variable QKD (CV-QKD) and device-independent QKD (DI-QKD) constrain chip metrics such as loss, modulation accuracy, state indistinguishability, phase stability, synchronization and security monitoring. It then compares planar lightwave circuit (PLC), silicon photonics, silicon nitride, thin-film lithium niobate, indium phosphide (InP) and heterogeneous platforms in terms of routing loss, modulation speed, stable interference, source integration and detector interfaces. Transmitter and receiver architectures, coherent detection, single-photon detection interfaces and on-chip monitoring are discussed as system-level building blocks. The review further analyses phase stability, packaging coupling, thermal management, polarization control, network coexistence and reliability, emphasizing that deployable QKD chips must remain calibratable and compatible with security models under realistic operation. Finally, system demonstrations, network deployment and practical security are discussed within a unified evaluation framework. Throughout, we argue that integration benefits QKD only when compact routing, stable interference, calibration access and manufacturable packaging jointly keep the device inside the assumptions of its security proof; accordingly, chip performance should be judged by mapped, calibratable security parameters rather than by integration density alone.
A complete chip-based quantum communication system is demonstrated. The core functions of quantum transmitter, quantum receiver and quantum random number generator are implemented onto photonic integrated circuits (PICs) of different materials. For the first time, these PICs are all interfaced in a compact optoelectronic assembly where they operate synchronously to distribute information theoretically secure encryption keys in real-time. After reviewing the challenges of system integration for quantum photonic circuits, we present our development of plug-and-play quantum communication modules that are practical, scalable, power efficient and perform with high stability under real-life conditions.