Nonlinear quantum photonics serves as a cornerstone in photonic quantum technologies, such as universal quantum computing and quantum communications. The emergence of an integrated photonics platform not only offers the advantage of large-scale manufacturing but also provides a variety of engineering methods. Given the complexity of integrated photonics engineering, a comprehensive simulation framework is essential to fully harness the potential of the platform. In this context, we introduce a nonlinear quantum photonics simulation framework, which can accurately model a variety of features such as adiabatic waveguide, material anisotropy, linear optics components, photon losses, and detectors. Furthermore, utilizing the framework, we have developed a device scheme, chip-scale temporal walk-off compensation, that is useful for various quantum information-processing tasks. We further show that the proposed device scheme can enhance the squeezing parameter of photon-pair sources and the conversion efficiency of quantum frequency converters without relying on higher pump power.
Nonlinear quantum photonics serves as a cornerstone in photonic quantum technologies, such as universal quantum computing and quantum communications. The emergence of an integrated photonics platform not only offers the advantage of large-scale manufacturing but also provides a variety of engineering methods. Given the complexity of integrated photonics engineering, a comprehensive simulation framework is essential to fully harness the potential of the platform. In this context, we introduce a nonlinear quantum photonics simulation framework, which can accurately model a variety of features such as adiabatic waveguide, material anisotropy, linear optics components, photon losses, and detectors. Furthermore, utilizing the framework, we have developed a device scheme, chip-scale temporal walk-off compensation, that is useful for various quantum information-processing tasks. We further show that the proposed device scheme can enhance the squeezing parameter of photon-pair sources and the conversion efficiency of quantum frequency converters without relying on higher pump power.
Chip-scale integrated photonic circuits provide an attractive platform for the implementation of many quantum photonic technologies ranging from precise metrology to secure communication and quantum computation. In particular, silicon photonic platforms support micron-scale nonlinear optical sources of non-classical light which can be mass manufactured using the robust fabrication processes pioneered by the CMOS microelectronics industry. Integration of these quantum photonic sources with high-performance classical photonic devices on the same chip is required for truly scalable quantum information technologies. Integrated nonlinear resonators are investigated as sources of quantum mechanically correlated photon pair sources. An all-order dispersion engineering method is presented as a robust design synthesis for micoring sources. In addition, a novel concept of coupled mode dispersion compensation is proposed and demonstrated, providing significantly improved performance characteristics of resonant four-wave mixing sources. Next a photon pair source is demonstrated in a commercial CMOS microelectronics process opening the door to future integration of quantum photonics with electronic logic and control circuits. Classical nonlinear optical measurements of stimulated four-wave mixing are used for the first time to accurately predict the quantum correlations from the same device operating in the photon pair regime. Next the first demonstration of fully on-chip pump rejection is demonstrated with over 95 dB pump extinction improving the figures of merit from previous demonstrations by multiple orders of magnitude, including losses, detected pair rates and size. Finally, proposals for introducing novel degrees of freedom provided by an integrated platform are presented for further improving the performance of both photon pair and classical nonlinear optical sources.
Nonclassical states of light are an essential resource for many emerging quantum technologies and applications ranging from information processing, encrypted communications, and networking to sensing, metrology, and imaging. Nonlinear optical processes in solid-state materials are widely used for generating quantum light, including single photons, entangled-photon pairs, and quadrature-squeezed states. Recent advances in nonlinear photonics have enabled the functionality of benchtop nonlinear instruments to be scaled down to a single chip without sacrificing efficiency or degrading the key performance metrics. The dramatic improvement in the size, weight, power, cost, and stability enabled by photonic integrated circuits has been essential for enabling the chip-scale generation, manipulation, and detection of quantum light at a steadily increasing degree of complexity and scale. Within the last decade, the authors have seen the progression from few-component photonic circuits operating on two photons to arrays of 18 identical heralded single-photon sources and reconfigurable devices operating with more than 650 components for multidimensional entanglement and arbitrary two-photon quantum gates. In this review, the authors summarize the history and recent key technological developments of chip-scale nonlinear quantum light generation based on integrated nonlinear photonics, recent advances in heterogeneous integrated methods, and approaches for system-level integration and demonstrated applications.
In the last few decades, there has been much progress on low loss waveguides, very efficient photon-number detectors and nonlinear processes. Engineered sum-frequency conversion is now at a stage where it allows operation on arbitrary temporal broadband modes, thus making the spectral degree of freedom accessible for information coding. Hereby the information is often encoded into the temporal modes of a single photon. Here, we analyse the prospect of using multi-photon states or squeezed states in different temporal modes based on integrated optics devices. We describe an analogy between mode-selective sum-frequency conversion and a network of spatial beam splitters. Furthermore, we analyse the limits on the achievable squeezing in waveguides with current technology and the loss limits in the conversion process.This article is part of the themed issue 'Quantum technology for the 21st century'.
Nonlinear photonics studies situations in which light passing through a material can be used to create, reshape, or convert other light in ways that are not possible in ordinary optical systems. In recent years, this has become especially important for quantum photonics, where carefully prepared states of light are used as resources for emerging technologies such as secure communication, ultra-precise measurement, and new forms of information processing. A major challenge, however, is that these effects are delicate, difficult to control, and highly sensitive to the imperfections that arise when trying to build practical devices on a chip. This thesis examines how such nonlinear quantum-optical processes can be both engineered more deliberately and modelled more realistically, with the broader goal of helping move quantum photonic technology from proof-of-principle laboratory demonstrations toward robust and scalable implementation. To do this, the thesis first places nonlinear quantum photonics in a broader technological context and explains the main physical ideas needed to understand how quantum states of light are generated, transformed, and measured. It then develops this picture through a set of concrete examples. These include a method for generating quantum light on a chip while avoiding one of the field’s standard fabrication steps, a proposed chip-scale device that could help connect otherwise incompatible quantum systems by changing the colour and spectral width of light, and a modelling framework that links quantum theory directly to realistic fabricated waveguides, including common imperfections such as loss, non-uniformity, and writing errors. The thesis also reviews a wider class of design methods in which the nonlinear properties of a material are deliberately patterned in order to tailor the light produced. Taken together, the central message is that progress in quantum photonics will depend not only on discovering new effects, but on learning how to design, fabricate, and model these devices in ways that make them practical outside idealized laboratory conditions.
Recent achievements in the area of integrated quantum optics and quantum information processing have shown impressive progress for the implementation of linear circuits based on monolithic waveguide structures. However, most experiments are based on χ(3)-media, such as glas, silicon-on insulator or silica-on-silicon. In these platforms the implementation of highly efficient sources, frequency converters and fast active phase shifters and modulators pose severe challenges. The use of advanced waveguides structures, which harness a χ(2)-non-linearity, allows for the realization various devices with multiple functionalities. These include single- and multi-channel sources with extraordinary brightness, quantum frequency conversion with tailored spectral-temporal properties, and complex circuitries comprising degenerate pair generation in orthogonal polarization, linear elements, and active elements such as polarization rotators or an electro-optically controllable time delay. Here we present our latest progress for the implementation of integrated devices based on χ(2)-media for quantum circuits and quantum communication systems.
Recent achievements in the area of integrated quantum optics and quantum information processing have shown impressive progress for the implementation of linear circuits based on monolithic waveguide structures. Most experiments are based on χ(3) -media, such as glas, silicon-on insulator or silica-on-silicon. In these platforms the implementation of highly efficient sources, frequency converters and fast active phase shifters and modulators pose severe challenges. The use of advanced waveguides structures, which harness a χ(2) –non-linearity, allows for the realization various devices with multiple functionalities. These include single- and multi-channel sources with high brightness, quantum frequency conversion with tailored spectral-temporal properties, and circuits comprising degenerate pair generation in orthogonal polarization, linear elements, and active elements such as polarization rotators or an electro-optically controllable time delay. Here we present our latest progress for the implementation of integrated devices based on χ(2) –media for quantum circuits and quantum communication systems.