Abstract The high stability and scalability of integrated circuits make them a reliable and practical platform for photonic quantum information processing. In various platforms for quantum photonic integrated circuits, the silicon‐on‐insulator technology, with its strong nonlinear effect and mature fabrication technology, has gradually emerged in the preparation of quantum photonic sources. This report presents a review of this series of research advances in the preparation of a quantum photonic source, based on the spontaneously four‐wave mixing process in a silicon waveguide, especially chip‐scale entangled states that have been realized in recent years.
Abstract The high stability and scalability of integrated circuits make them a reliable and practical platform for photonic quantum information processing. In various platforms for quantum photonic integrated circuits, the silicon‐on‐insulator technology, with its strong nonlinear effect and mature fabrication technology, has gradually emerged in the preparation of quantum photonic sources. This report presents a review of this series of research advances in the preparation of a quantum photonic source, based on the spontaneously four‐wave mixing process in a silicon waveguide, especially chip‐scale entangled states that have been realized in recent years.
Abstract Integrated quantum photonics is now seen as one of the promising approaches to realize scalable quantum information systems. With optical waveguides based on silicon photonics technologies, we can realize quantum optical circuits with a higher degree of integration than with silica waveguides. In addition, thanks to the large nonlinearity observed in silicon nanophotonic waveguides, we can implement active components such as entangled photon sources on a chip. In this paper, we report recent progress in integrated quantum photonic circuits based on silicon photonics. We review our work on correlated and entangled photon‐pair sources on silicon chips, using nanoscale silicon waveguides and silicon photonic crystal waveguides. We also describe an on‐chip quantum buffer realized using the slow‐light effect in a silicon photonic crystal waveguide. As an approach to combine the merits of different waveguide platforms, a hybrid quantum circuit that integrates a silicon‐based photon‐pair source and a silica‐based arrayed waveguide grating is also presented.
There has been a strong interest to translate optical quantum technologies into photonic integrated circuits (PICs) as they could provide a stable, compact, and potentially scalable architecture for generating, manipulating, and measuring optical quantum states. Among the various PIC technologies that are being developed, silicon-on-insulator (SOI) PICs have several advantages, including technologically mature foundry fabrication, CMOS-process integration, and high-performance switches, modulators, polarization control, filters, and other essential optical components. However, several components are missing that are needed for quantum information processing tasks. Here, we describe recent progress on augmenting SOI PICs with essential capabilities for photonic quantum technologies — entangled photon sources, single photon detectors, and reconfigurable linear optics unitary transformations — and focus on two central application areas: quantum communications and quantum 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.
Abstract Quantum information science offers inherently more powerful methods for communication, computation, and precision measurement that take advantage of quantum superposition and entanglement. In recent years, theoretical and experimental advances in quantum computing and simulation with photons have spurred great interest in developing large photonic entangled states that challenge today’s classical computers. As experiments have increased in complexity, there has been an increasing need to transition bulk optics experiments to integrated photonics platforms to control more spatial modes with higher fidelity and phase stability. The silicon‐on‐insulator (SOI) nanophotonics platform offers new possibilities for quantum optics, including the integration of bright, nonclassical light sources, based on the large third‐order nonlinearity (χ (3) ) of silicon, alongside quantum state manipulation circuits with thousands of optical elements, all on a single phase‐stable chip. How large do these photonic systems need to be? Recent theoretical work on Boson Sampling suggests that even the problem of sampling from e30 identical photons, having passed through an interferometer of hundreds of modes, becomes challenging for classical computers. While experiments of this size are still challenging, the SOI platform has the required component density to enable low‐loss and programmable interferometers for manipulating hundreds of spatial modes. Here, we discuss the SOI nanophotonics platform for quantum photonic circuits with hundreds‐to‐thousands of optical elements and the associated challenges. We compare SOI to competing technologies in terms of requirements for quantum optical systems. We review recent results on large‐scale quantum state evolution circuits and strategies for realizing high‐fidelity heralded gates with imperfect, practical systems. Next, we review recent results on silicon photonics‐based photon‐pair sources and device architectures, and we discuss a path towards large‐scale source integration. Finally, we review monolithic integration strategies for single‐photon detectors and their essential role in on‐chip feed forward operations.
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.
Silicon-on-insulator (SOI) wafers have been developed for electronic integrated circuits, but are also one of the most promising platforms in photonic integrated circuits due to its low loss, high refractive index, ability to fast phase modulation, and well-developed fabrication technologies. With advantages to handle light with a small volume and high modulation speed, silicon photonics has been intensively investigated as the next generation platform of signal processing, interconnection, and communication devices. Recently, silicon photonics has been attracted great interests in quantum optics communities as optical quantum systems for linear optical quantum computing are achievable using silicon photonic components including beam splitters, phase modulators, and filters and the small footprint of a silicon photonic quantum system has unprecedented performances of high stability and scalability. Here we show our recent results on the fabrication of silicon photonic elements for quantum applications. We fabricated low-loss optical waveguides, efficient fiber-to-waveguide grating couplers, resonator-based optical filters, and tunable beam splitters and tested their performances. A micro-sized heater is attached on a Mach-Zehnder interferometer, showing stable operation as a slow phase modulator. In addition, phase modulators using plasma dispersion effects are under investigation. Finally, the quantum characteristics of photon pairs generated by spontaneous four-wave mixing in silicon waveguides are investigated. These results will be an essential cornerstone for the realization of quantum optical computing and quantum communication devices.