Quantum key distribution (QKD) is nowadays a well established method for generating secret keys at a distance in an information-theoretic secure way, as the secrecy of QKD relies on the laws of quantum physics and not computational complexity. In order to industrialize QKD, low-cost, mass-manufactured and practical QKD setups are required. Hence, photonic and electronic integration of the sender's and receiver's respective components is currently in the spotlight. Here we present a high-speed (2.5 GHz) integrated QKD setup featuring a transmitter chip in silicon photonics allowing for high-speed modulation and accurate state preparation, as well as a polarization-independent low-loss receiver chip in aluminum borosilicate glass fabricated by the femtosecond laser micromachining technique. Our system achieves raw bit error rates, quantum bit error rates and secret key rates equivalent to a much more complex state-of-the-art setup based on discrete components.
Quantum key distribution (QKD) is nowadays a well established method for generating secret keys at a distance in an information-theoretic secure way, as the secrecy of QKD relies on the laws of quantum physics and not computational complexity. In order to industrialize QKD, low-cost, mass-manufactured and practical QKD setups are required. Hence, photonic and electronic integration of the sender's and receiver's respective components is currently in the spotlight. Here we present a high-speed (2.5 GHz) integrated QKD setup featuring a transmitter chip in silicon photonics allowing for high-speed modulation and accurate state preparation, as well as a polarization-independent low-loss receiver chip in aluminum borosilicate glass fabricated by the femtosecond laser micromachining technique. Our system achieves raw bit error rates, quantum bit error rates and secret key rates equivalent to a much more complex state-of-the-art setup based on discrete components.
Quantum key distribution (QKD) is nowadays a well-established method for generating secret keys at a distance in an information-theoretically secure way, as the secrecy of QKD relies on the laws of quantum physics and not on computational complexity. In order to industrialize QKD, low-cost, mass-manufactured, and practical QKD setups are required. Hence, photonic and electronic integration of the sender’s and receiver’s respective components is currently in the spotlight. Here we present a high-speed (2.5 GHz) integrated QKD setup featuring a transmitter chip in silicon photonics allowing for high-speed modulation and accurate state preparation, as well as a polarization-independent low-loss receiver chip in aluminum borosilicate glass fabricated by the femtosecond laser micromachining technique. Our system achieves raw bit error rates, quantum bit error rates, and secret key rates equivalent to a much more complex state-of-the-art setup based on discrete components [ Boaron A. et al. , Phys. Rev. Lett. 121 , 190502 ( 2018 ) ].
Advances in quantum computing pose significant threats to the security of conventional encryption standards. Although quantum key distribution systems offer inherent security, they face challenges in achieving practical secret-key rates over long transmission distances. Photonic Integrated Circuit technologies provide scalability and system efficiency for high key rates using multiplexed time-bin protocols. We present the architecture of a 16-channel multiplexed QKD system at a GHz clock rate realized on integrated photonic chips, promising further scalability. The sender module revolves around an indium-phosphide chip featuring tunable lasers, modulators, and combiners. On the receiver side, low fiber-to-chip coupling loss and waveguide-integrated superconducting nanowire single-photon detectors on silicon nitride provide the necessary detection efficiency.
Quantum key distribution (QKD) provides information-theoretic security based on the laws of quantum mechanics, offering resistance to future computational threats, including quantum computers. While QKD technology shows great promise, its widespread adoption depends heavily on achieving both high performance and system-level practicality. In this work, we report an integrated silicon photonics-based QKD system that achieves a secret key rate of 1.213Gbits −1 , with composable security and finite-size analysis, over a metropolitan distance of 10 km with polarization multiplexing. Our contributions are twofold. First, at the quantum optical layer, we develop an on-chip quantum transmitter and receiver that operate at 40 Gbaud at room temperature, featuring high-performance balanced homodyne detection using low-noise amplifiers with off-the-shelf RF components. Second, we implement a discrete-modulated continuous variable (DM CV) QKD protocol that simplifies hardware requirements and leverages standard telecommunication components, and design a polar-code-based information reconciliation algorithm specifically optimized for DM CV QKD and amenable to real-time implementation. Our results demonstrate a cost-effective QKD solution that achieves high key rates through integrated photonics operating at room temperature with off-the-shelf RF components and digital signal processing for robust operation. We anticipate that this research will pave the way for large-scale quantum secure networks.
Quantum key distribution (QKD) provides information-theoretic security independent of computational assumptions, yet the bulk and cost of current systems hinder large-scale deployment. Although integrated photonic technologies have enabled highly integrated QKD chips, practical QKD transmitters are still predominantly implemented as rack-mounted systems. Here, we demonstrate a highly integrated standalone QKD transmitter that integrates all essential functionalities required for practical QKD operation within a compact platform built around a silicon photonic encoding chip. The transmitter occupies only 167×56×21mm3 (∼0.2dm3), comparable in size to a half-height, half-width PCIe card and more than 30 times smaller in volume than a conventional 1U rack-mounted system. Paired with a conventional discrete-component receiver, it achieves a secure key rate of 219.1 kbps over 51.3 km of standard single-mode fiber, with performance comparable to that of conventional discrete-component implementations. This work bridges the gap between photonic chip integration and deployable QKD hardware, marking an important step toward transitioning QKD transmitters from conventional rack-mounted equipment to compact board-level platforms.
Abstract Quantum key distribution (QKD) has made significant advancements over the past few decades and is gradually transitioning from laboratory to industrial domain. This transformation process poses urgent demands for integrated, cost‐effective, and mass‐producible QKD devices. Here, by interfacing a laser diode, a QKD encoding photonics chip, and their associated electronics driver chips, the QKD transmitter has been condensed from several bulky discrete components to integrated modules with dimensions of a few centimeters, while the modulation rate of the transmitter has been enhanced to 3.33 GHz. Based on this transmitter, QKD is demonstrated over a 100 km standard fiber channel, capable of generating secure keys at a record high key rate of 2.82 Mbps over this distance. This work demonstrates the feasibility of high‐speed integrated QKD transmitters, thereby further propelling the research on QKD in practical applications.
Measurement-device-independent quantum key distribution (MDI QKD) removes all detector side channels and enables secure QKD with an untrusted relay.It is suitable for building a star-type quantum access network, where the complicated and expensive measurement devices are placed in the central untrusted relay and each user requires only a low-cost transmitter, such as an integrated photonic chip.Here, we experimentally demonstrate a 1.25-GHz silicon photonic chip-based MDI QKD system using polarization encoding.The photonic chip transmitters integrate the necessary encoding components for a standard QKD source.We implement random modulations of polarization states and decoy intensities, and demonstrate a finite-key secret rate of 31 bit=s over 36-dB channel loss (or 180-km standard fiber).This key rate is higher than state-of-the-art MDI QKD experiments.The results show that silicon photonic chipbased MDI QKD, benefiting from miniaturization, low-cost manufacture, and compatibility with CMOS microelectronics, is a promising solution for future quantum secure networks.