Photonics has been identified as a highly promising platform for optical classical and quantum computing. In the realm of classical computing, the inherent parallelism of optics, as opposed to the sequential operations of electronics, offers significant potential for achieving faster and more energy-efficient computational capabilities. Photonics also represents a highly advantageous option for the pursuit of integrated quantum computing, primarily due to the noise- and decoherence-free nature of single photons. Optical qubits can be effectively generated by encoding single photons in a given degree of freedom, such as polarization, path, or wavelength. Path encoded programmable quantum gates have already been realized in Silicon Photonics (SiPh), a technology platform offering several appealing features such as compatibility with complementary metal oxide semiconductor (CMOS) for high integration density. To achieve a large-scale photonic quantum system, encoding the information on other degrees of freedom, such as polarization and transverse mode, is essential. Here, we present an open access process design kit (PDK) for multi-transverse-mode components compatible with standard 220 nm thick SiPh technology. Then, we discuss the use of the PDK components in developing multi-transverse-mode classic optical computing. We also investigate multiple transverse modes of light for encoding and manipulating information in quantum photonics.
Photonics has been identified as a highly promising platform for optical classical and quantum computing. In the realm of classical computing, the inherent parallelism of optics, as opposed to the sequential operations of electronics, offers significant potential for achieving faster and more energy-efficient computational capabilities. Photonics also represents a highly advantageous option for the pursuit of integrated quantum computing, primarily due to the noise- and decoherence-free nature of single photons. Optical qubits can be effectively generated by encoding single photons in a given degree of freedom, such as polarization, path, or wavelength. Path encoded programmable quantum gates have already been realized in Silicon Photonics (SiPh), a technology platform offering several appealing features such as compatibility with complementary metal oxide semiconductor (CMOS) for high integration density. To achieve a large-scale photonic quantum system, encoding the information on other degrees of freedom, such as polarization and transverse mode, is essential. Here, we present an open access process design kit (PDK) for multi-transverse-mode components compatible with standard 220 nm thick SiPh technology. Then, we discuss the use of the PDK components in developing multi-transverse-mode classic optical computing. We also investigate multiple transverse modes of light for encoding and manipulating information in quantum photonics.
Silicon photonics is a dynamic research field of integrated optics. It allows to miniaturize numerous optical functionalities such as lasers, electro-optical modulators, routers, detectors, for telecom wavelengths, LIDAR, sensor, metrology or even spectroscopy, all while been able to propose large scale production high precision technologies. On another side, quantum optics suffers from difficulties to scale optical systems, requires extreme stability, perfect alignment, and many bulky optical elements, while solving these issues follows a natural path in integrated photonics. Development of integrated quantum photonics can thus open the door to cheap, powerful, and scalable systems for quantum cryptography, telecoms, and computation. In a significant way, quantum requirements are not the ones of classical circuits with respect to photonic components and circuits. The generation of quantum states indeed requires more than 100dB of pump laser rejection, while being able to manage ultra-low useful optical signals and get rid of on-chip optical noise. In this context, this thesis is dedicated to the study, dimension, realization, and characterization of silicon photonic components and circuits for quantum optics on a chip. The target goal is to generate entangled states in energy-time and manipulate them on chip. The qualification of the quantum properties is also explored to better understand the limitations of the silicon platform in the followed objectives. Another choice of this work is to stay in telecoms wavelength and aligned with the standard channels (ITU grid), to only use off-the-shelf components, all while been CMOS compatible and compliant with standard fabrication process, this to allow the possibility to produce on large scale.
The capability of realizing quantum photonics implementations on-chip will have a strong impact on several aspects of quantum computation and information processing. The implementation of large scale integrated quantum photonic technologies requires on-chip reconfigurable waveguide circuits as well as single-photon sources and detectors. Many successes have been made in recent years to demonstrate complex quantum circuits in many material platforms. Among all these platforms, the Silicon-on-Insulator (SOI) platform is outstanding as it is well developed for classical applications and therefore deploys a high component density, mature fabrication techniques and compatibility with the telecom regime and the complementary metal-oxide-semiconductor (CMOS) technology. However, the lack of on-demand non-classical light sources, directly incorporated in silicon chips, forces the use of nonlinear processes to generate non-classical light states: the probabilistic nature of the emission process sets a limit in the maximally achievable experimental complexity. The use of on-demand sources will have a strong impact on the device’s scalability.
The field of high-dimensional quantum photonics involves the use of multimode photonic degrees-of-freedom such as the spatial, temporal, or spectral structure of light to encode multi-level quantum states. Recent years have seen rapid progress in the development of methods to generate, manipulate, and distribute such quantum states of light and their use in a range of quantum technology applications that offer practical advantages over conventional qubit-based approaches. High-dimensional quantum states of light encoded in photonic time-bins, frequency-bins, transverse-spatial modes, waveguide paths, and temporal modes have enabled noise-robust fundamental tests of quantum mechanics, error-resilient and high-capacity quantum communication protocols, andas well as efficient approaches for quantum information processing, to name just a few examples. However, research in this field has progressed fairly independently, with little exchange across different photonic degrees-of-freedom or between experiment and theory and no comprehensive comparison between degrees-of-freedom. This roadmap aims to bridge this gap by surveying progress in each area and identifying shared challenges and opportunities that cut across two or more photonic degrees-of-freedoms. We review early work and state-of-the-art experimental techniques under development for high-dimensional quantum states encoded in single and entangled photons, as well as theoretical tools for their measurement and certification. We outline the main outstanding challenges for theory and each experimental degree-of-freedom, identifying promising future directions of research that may enable these to be overcome. We end by discussing interconnections and shared challenges centered around their distribution, measurement, and manipulation, with a view towards their integration into next-generation quantum technology platforms and applications.
Silicon quantum photonics is a promising platform for the development of advanced quantum information technologies, offering a high level of stability, controllability, scalability and integration density. Silicon quantum photonics has enabled a range of key demonstrations including the development of a versatile toolbox for controlling single-photon’s different degrees of freedom, the generation of multipartite entanglement and high-dimensional entanglement, and realization of large-scale programmable quantum devices. The progress has unlocked the unprecedented power of chip-scale quantum photonic technologies for advanced applications in quantum communication, computing and simulation.
Abstract Quantum photonic system has made remarkable achievements in computing and communication. Serving as quantum information carriers, photons are flying qubits and robust against decoherence, emerging as a desirable platform to make quantum processor a reality. However, with system's complexity and functionality scaling up, the requirements for stability, programmability, and manufacturability will be in high demand. Integrated photonics, compatible with complementary metal‐oxide‐semiconductor fabrication, has overwhelming dominance in terms of density and performance, making it an unrivaled contender for large‐scale quantum information processing (QIP). To improve the performance of individual blocks and integrate them on a common substrate is one of the core tasks for a practical quantum processor. Here, the recent advances in components that constitute quantum photonic systems on silicon photonics platform, including sources, modulators, and detectors are reviewed. Burgeoning quantum photonics applications, such as multi‐dimensional, multi‐photon QIP and integrated quantum key distribution are highlighted.
Quantum technologies have surpassed classical systems by leveraging the unique properties of superposition and entanglement in photons and matter. Recent advancements in integrated quantum photonics, especially in silicon-based and lithium niobate platforms, are pushing the technology toward greater scalability and functionality. Silicon circuits have progressed from centimeter-scale, dual-photon systems to millimeter-scale, high-density devices that integrate thousands of components, enabling sophisticated programmable manipulation of multi-photon states. Meanwhile, lithium niobate, thanks to its wide optical transmission window, outstanding nonlinear and electro-optic coefficients, and chemical stability, has emerged as an optimal substrate for fully integrated photonic quantum chips. Devices made from this material exhibit high efficiency in in generating, manipulating, converting, storing, and detecting photon states, thereby establishing a basis for deterministic multi-photon generation and single-photon quantum interactions, as well as comprehensive frequency-state control. This review explores the development of integrated photonic quantum technologies based on both silicon and lithium niobate, highlighting invaluable insights gained from silicon-based systems that can assist the scaling of lithium niobate technologies. It examines the functional integration mechanisms of lithium niobate in electro-optic tuning and nonlinear energy conversion, showcasing its transformative impact throughout the photonic quantum computing process. Looking ahead, we speculate on the developmental pathways for lithium niobate platforms and their potential to revolutionize areas such as quantum communication, complex system simulation, quantum sampling, and optical quantum computing paradigms.