There is growing incentive to integrate quantum communication technologies into our high-bandwidth communication networks. However, for a realistic and practical large-scale deployment, drastic reductions of the size, cost and power consumption of current quantum cryptographic systems are necessary. We show how this goal can be achieved using photonic integration. We demonstrate quantum communication chips capable of record performances including quantum key distribution at 250kb/s over a 20dB-loss channel and quantum random number generation at 8Gb/s. The scalability and affordability of these new devices will allow the deployment of quantum cryptography in high connectivity networks.
There is growing incentive to integrate quantum communication technologies into our high-bandwidth communication networks. However, for a realistic and practical large-scale deployment, drastic reductions of the size, cost and power consumption of current quantum cryptographic systems are necessary. We show how this goal can be achieved using photonic integration. We demonstrate quantum communication chips capable of record performances including quantum key distribution at 250kb/s over a 20dB-loss channel and quantum random number generation at 8Gb/s. The scalability and affordability of these new devices will allow the deployment of quantum cryptography in high connectivity networks.
Abstract Quantum key distribution (QKD) has convincingly been proven compatible with real life applications. Its wide-scale deployment in optical networks will benefit from an optical platform that allows miniature devices capable of encoding the necessarily complex signals at high rates and with low power consumption. While photonic integration is the ideal route toward miniaturisation, an efficient route to high-speed encoding of the quantum phase states on chip is still missing. Consequently, current devices rely on bulky and high power demanding phase modulation elements which hinder the sought-after scalability and energy efficiency. Here we exploit a novel approach to high-speed phase encoding and demonstrate a compact, scalable and power efficient integrated quantum transmitter. We encode cryptographic keys on-demand in high repetition rate pulse streams using injection-locking with deterministic phase control at the seed laser. We demonstrate record secure-key-rates under multi-protocol operation. Our modulator-free transmitters enable the development of high-bit rate quantum communications devices, which will be essential for the practical integration of quantum key distribution in high connectivity networks.
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) 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.
Quantum key distribution (QKD) relies on the fundamental principles of quantum mechanics and can theoretically achieve unconditionally secure communication that is provable by information theory. Quantum random number generators, on the other hand, utilize the inherent randomness of quantum phenomena and are capable of generating a truly random entropy source that is unpredictable, unbiased and unrepeatable. These two technologies are crucial for building highly trustworthy and secure communication systems resistant to quantum attacks. However, their large-scale deployment still faces challenges such as system performance optimization, cost control and scale production. Relying on wafer-level fabrication platforms and micro-nanometer processing, integrated photonics technology integrates the core devices of traditional QKD systems (e.g., light source, modulator, and detector) in a single chip at high density. It significantly improves the miniaturization, operational stability and cost-effectiveness of the system, and enhances the intrinsic security, and becomes a key enabling platform to drive QKD and QRNG from laboratory to engineering applications. In this paper, we systematically review the recent breakthroughs of photonic integrated QKD based on different material platforms (SOI/InP/TFLN/Si3N4) in terms of core metrics, such as transmission distance and key rate, as well as the significant breakthroughs of integrated QRNG in terms of random number generation rate and system integration. Finally, the future development direction of this field is discussed and outlooked from the four dimensions of practical security of QKD systems, on-chip implementation of cutting-edge QKD protocols, practical fully-integrated QKD systems, and synergistic optimization of high performance and high integration of integrated QRNG.
Abstract Quantum communication networks enable applications ranging from highly secure communication to clock synchronization and distributed quantum computing. Miniaturized, flexible, and cost-efficient resources will be key elements for ensuring the scalability of such networks as they progress towards large-scale deployed infrastructures. Here, we bring these elements together by combining an on-chip, telecom-wavelength, broadband entangled photon source with industry-grade flexible-grid wavelength division multiplexing techniques, to demonstrate reconfigurable entanglement distribution between up to 8 users in a resource-optimized quantum network topology. As a benchmark application we use quantum key distribution, and show low error and high secret key generation rates across several frequency channels, over both symmetric and asymmetric metropolitan-distance optical fibered links and including finite-size effects. By adapting the bandwidth allocation to specific network constraints, we also illustrate the flexible networking capability of our configuration. Together with the potential of our semiconductor source for distributing secret keys over a 60 nm bandwidth with commercial multiplexing technology, these results offer a promising route to the deployment of scalable quantum network architectures.