The interaction of light with matter can generate different types of scattering that can be applied to quantum optics, photonics and integrated optics appropriately. The generation of certain pulses in certain waveguides can produce certain nonlinear optical pulses with important properties such as low energy and information loss applied, for example, to communication systems and quantum information. The method we describe is based on the generation and propagation of nonlinear optical pulses in multidimensional material structures: waveguides in 1 dimension, planar systems in 2 dimensions and crystalline systems in 3 dimensions. These structures can be appropriately designed to generate nonlinear and quantum optical pulses depending on the crystal structure and electrical susceptibility of the material. These optical pulses can be appropriately characterized whose respective scattering signals can be identified and processed providing an application basis for emerging technologies for transmission and processing systems based on quantum optics and quantum computing.
The interaction of light with matter can generate different types of scattering that can be applied to quantum optics, photonics and integrated optics appropriately. The generation of certain pulses in certain waveguides can produce certain nonlinear optical pulses with important properties such as low energy and information loss applied, for example, to communication systems and quantum information. The method we describe is based on the generation and propagation of nonlinear optical pulses in multidimensional material structures: waveguides in 1 dimension, planar systems in 2 dimensions and crystalline systems in 3 dimensions. These structures can be appropriately designed to generate nonlinear and quantum optical pulses depending on the crystal structure and electrical susceptibility of the material. These optical pulses can be appropriately characterized whose respective scattering signals can be identified and processed providing an application basis for emerging technologies for transmission and processing systems based on quantum optics and quantum computing.
We present a new class of solutions based on quantum optical scattering in certain optical structures that may be applied in the development of photonic devices in one and two spatial dimensions. These devices may act as sensors for optical fibers by selecting appropriate wavelengths and acting as noise suppression for integrated devices and in the processing of quantum optical signals. We highlight that quantum optical scattering can be adequately modeled in order to describe the typical nonlinear optical effects of the photonic device and capable of describing a type of entanglement between Raman and Brillloin scatterings. This modeling among other applications could open a new window for hybrid sensors based on nonlinear optical effects in photonic optical structures and quantum optical scattering.
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.
Optical fibers are the backbone of the world's communication systems. They also represent the simplest example of a photonic device, where photons in waveguides replace electrons in wires. More sophisticated devices than this can be made, in which all the optical components – including multiple waveguided modes – are integrated on a chip. It is important to understand the quantum noise properties of these systems. While in some respects these systems can be treated as one-dimensional, there are additional features. Dispersion is due not just to material properties, but also to the waveguide geometry. The nonlinearity comes from a combination of material and geometric properties as well. There is, of course, a quantum aspect to these photonic devices, in which quantum noise occurs due to random effects caused by nonlinearity and gain. Optical devices based on waveguides are, of course, not just simple fibers. One can have multiple waveguides with various types of linear coupling. The intrinsic nonlinearity of the dielectric leads to four-wave mixing, which can be an important source of correlated photons, both for fundamental tests of quantum mechanics, and for applications in quantum information. It is often essential to include effects due to anisotropies of various types, as well as material dispersion. In dielectrics, another effect that should be included is the coupling of vibrational modes of the (solid) dielectric to the propagating field, which gives rise to Raman and Brillouin scattering effects. This allows us to obtain a more detailed and correct theory of quantum noise than the simplified case treated in Chapter 3.
Quantum optics unites physical optics and the quantum field theory of light. A fundamental consequence of light-field quantization is the appearance of vacuum fluctuations, or quantum noise, which has no classical analogue and stems from the Heisenberg uncertainty relations. Nonlinear optical interactions "on a chip" offer new, unexplored functionalities, and may play a key role in future technologies. In this respect, a major theoretical and computational challenge is the development of new, tractable models of the nonlinear quantum dynamics in realistic devices with complex geometries in multiple dimensions. Description of nonlinear pulse propagation, interaction, and localization phenomena in multiple dimensions requires dipole coupling to at least a 2D resonant medium, whereby the electric field of a single-photon excitation is coupled to at least two distinct dipole optical transitions. The chapter applies the vector Maxwell-pseudospin formalism to the problem of nonlinear optical pulse propagation in planar waveguides and microcavities with embedded quantum systems.
It is well known that the scattering matrix plays an important role in quantum optics. This matrix converts the incoming characteristics of scattered radiation into output characteristics. Currently, only special cases of such a scattering matrix are known, which are determined by a specific problem. In this work, a general form of the scattering matrix is obtained, which can be applied to a wide range of problems. It is shown that previously well-known and widely used scattering matrices can be obtained from the resulting scattering matrix. The results obtained can be used to describe new quantum states, the scattering matrices of which have not yet been studied.
Ability to tune the group velocity of a light pulse is of great importance for optical communication applications and realization of quantum information processing. Tunability of group velocity can be achieved by using either optical or electronic resonances. Tunability of an optical resonance depends on the change in refractive index of the cavity material. However, since electro-optical coefficients of non-engineered materials are quite small, the tuning range of optical resonances by electric field is narrow. This makes tuning by electric field impractical for most applications. Quantum dot (QD) coupled to a photonic crystal cavity is a useful hybrid system exhibiting nonlinear features. In this work, we analyze the use of quantum dot - optical cavity hybrid systems to engineer nonlinear waveguides susceptible to electric fields. We start by theoretically analyzing the optical pulse propagation at low-photon number excitation limit in a periodically arranged strongly coupled quantum dot - photonic crystal system. A one dimensional periodic array of evanescently coupled photonic cavities (coupled resonator optical waveguides, CROWs) containing non-interacting quantum dots allows us to tune the group velocity and the bandwidth of the pulse by adjusting the cavity/QD coupling. Tunable group velocity can be achieved by applying an external electric field which will result in a significant decrease in the cavity/QD coupling because of DC Stark effect. We also show that, using this approach, light pulses can be slowed down or stored by compressing the pulse bandwidth adiabatically and reversibly. Adiabatic bandwidth compression can be achieved by slowly decreasing the coupling strength when the light pulse is inside the coupled resonator optical waveguide. The energy splitting and the coupling constant after applying electric field is calculated by using perturbation theory for two level systems. With our approach, nonlinear materials highly susceptible to electric fields can be engineered in low-excitation regime.