Nano-engineering is crucial in realizing compact photonic systems for light routing and conditioning with ever more complex optical functions. It also promises to elevate the precision of experiments in high-precision optical metrology to an unprecedented level, e.g., optical atomic clocks and gravitational wave detectors - the most precise experiments ever developed by humankind. In this contribution, I give an overview of the development and possibilities of nanophotonic devices for applications in precision optical experiments. I explain relevant physical phenomena of light-matter interaction and illustrate the role of material properties in these experiments.
Nano-engineering is crucial in realizing compact photonic systems for light routing and conditioning with ever more complex optical functions. It also promises to elevate the precision of experiments in high-precision optical metrology to an unprecedented level, e.g., optical atomic clocks and gravitational wave detectors - the most precise experiments ever developed by humankind. In this contribution, I give an overview of the development and possibilities of nanophotonic devices for applications in precision optical experiments. I explain relevant physical phenomena of light-matter interaction and illustrate the role of material properties in these experiments.
Measurements play a pivotal role in the advance of science and technology. To name just two examples, the global positioning system (GPS) technology relies on atomic clocks, and the detection of gravitational waves has been achieved via extremely precise interferometric measurements. The aim of my thesis is to contribute towards the goal of doing quantum metrology with nanophotonic structures. With this motivation, some problems across the fields of nanophotonics and quantum optics are tackled. First, the role of helicity within nanophotonics is explored. In the context of symmetries and conserved quantities, helicity, the projection of the total angular momentum on the linear momentum direction, is a useful addition to the more commonly considered quantities such as angular momentum. A simple but versatile experimental treatment of helicity is introduced and demonstrated on the scattering of focused light by circular nanoholes in a gold film. The helicity transformation that takes place in this light-matter interaction is studied. Another section is devoted to the topic of quantum light sources. It is shown how to influence and measure the spectrotemporal wave function of photon pairs by exploiting properties of the spontaneous parametric down-conversion (SPDC) process. The proposed technique also allows to determine the distribution of time delays between the two photons in a pair, which is typically a challenging experimental task. Finally, a quantum metrology experiment on the interaction of light with chiral molecules is presented. In this proof-of-concept experiment entangled photon pairs are used for the measurement of natural optical activity and its wavelength dependence, the optical rotatory dispersion.
An exciting frontier in quantum information science is the integration of otherwise "simple" quantum elements into complex quantum networks. The laboratory realization of even small quantum networks enables the exploration of physical systems that have not heretofore existed in the natural world. Within this context, there is active research to achieve nanoscale quantum optical circuits, for which atoms are trapped near nano-scopic dielectric structures and "wired" together by photons propagating through the circuit elements. Single atoms and atomic ensembles endow quantum functionality for otherwise linear optical circuits and thereby enable the capability of building quantum networks component by component. Toward these goals, we have experimentally investigated three different systems, from conventional to rather exotic systems : free-space atomic ensembles, optical nano fibers, and photonics crystal waveguides. First, we demonstrate measurement-induced quadripartite entanglement among four quantum memories. Next, following the landmark realization of a nanofiber trap, we demonstrate the implementation of a state-insensitive, compensated nanofiber trap. Finally, we reach more exotic systems based on photonics crystal devices. Beyond conventional topologies of resonators and waveguides, new opportunities emerge from the powerful capabilities of dispersion and modal engineering in photonic crystal waveguides. We have implemented an integrated optical circuit with a photonics crystal waveguide capable of both trapping and interfacing atoms with guided photons, and have observed the collective effect, superradiance, mediated by the guided photons. These advances provide an important capability for engineered light-matter interactions, enabling explorations of novel quantum transport and quantum many-body phenomena.
New paradigms for optical physics emerge with lattices of atoms trapped in one and two-dimensional photonic crystals [1-4]. Exemplary experimental platforms include photonic crystal waveguides [5-7] and cavities [8, 9]. Owing to their small optical loss and tight field confinement, these nanoscale dielectric devices are capable of mediating long-range atom-atom interactions using photons propagating in their guided modes. In a complimentary fashion, long-range interactions between photons can be mediated by an underlying lattice of atoms. Such systems have the potential to provide new tools for scalable quantum networks, quantum phases of light and matter, and quantum metrology. However, bringing this future of atom nanophotonics to fruition requires the creation of an interdisciplinary toolkit for the control, manipulation, and interaction of atoms and photons with a complexity and scalability not currently possible. I will give an overview of the theoretical prospects for new physics and review experimental progress in this nascent field at the interfaces of nano-photonics, atomic physics, and quantum optics.
Our ability to manipulate the coherence properties of light has been at the heart of many of the most important scientific and technological innovations of this century. There can hardly be a home in this country that does not possess a laser in the form of a compact disc player or a CDROM. When we talk on the phone, or send messages on the Internet, there is a high probability that our message will be encoded by a laser into pulses of light to be passed through optical fibres. In the last few years physicists have been discovering that it is possible to control the coherence properties of atoms, and are now developing tools analogous to those which have been developed to take advantage of the coherence properties of light. In the next decade we can look forward to seeing the application of lasers, fibres, mirrors and waveguides for atoms. Already we have been able to construct interferometry experiments using beams of atoms and these have proved to be extremely sensitive measurement devices, allowing us to test physical theories and measure fundamental constants to a level of precision not previously possible. Will these developing technologies ever be as ubiquitous as their optical forebears? In this paper we discuss the anticipated uses of this technology for both fundamental science and industrial applications. Starting from an explanation of the meaning of coherence and a comparison of the properties of photons and atoms, we describe the development of the science of atom optics. The tortuous route towards the great achievement of producing a Bose–Einstein condensate is described, and we explain why this is the most important step towards a laser–like source of atoms. Numerous other optical elements for atoms have been built or are on the drawing board, and we describe how these may be used to manipulate atoms with a precision that has never before been achieved, and look ahead to what we can learn about physics using these tools and at how they can be put to practical use.
Development of technology can allow access to new regimes in science and creation of new fields of research. The development of ultra-high finesse mirror technology enabled the development of the field of cavity quantum electrodynamics, and an abundance of wonderful physics experiments soon followed. The sophistication of the field of nano-fabrication and nano-photonics would allow unprecedented capability to mold the shape and flow of light, and provide a novel platform for efficient and hopefully integrable quantum systems. In this project, we hope to interface cold atoms, perhaps the most quintessential of quantum systems, to the engineering power of nano-photonics. We believe this field of study will not only lead to the demonstration of new physics in the quantum regime, but work toward building a network with quantum capabilities mediated by optical channels. In this project, we develop a nano-fabricated platform capable of interfacing nano-photonic devices with cold Cesium atoms in free-space. Nano-photonic waveguide devices are fabricated in a Silicon Nitride device layer on Silicon substrate. The fabrication is compatible with conventional semiconductor fabrication processes, and the chip design has been adapted to allow incorporation with free-space optics to support cold Cesium atom cloud around the waveguides. An ultra-high vacuum system that is compatible to the chip and its supporting structures was constructed to perform experiments. With our system, we were able to fabricate and characterize nano-photonic structures, including 1D photonic crystal waveguides, cavities, and 2D photonic crystal slabs. For the 1D photonic crystal waveguide devices, enhanced atom-light coupling between localized Cesium atoms in the vicinity of the devices, and also atom-atom interaction between Cesium atoms mediated by the guided mode of the photonic crystal waveguide, has been observed. The 2D photonic devices allow us many capabilities beyond that of the 1D waveguide. Demonstration of exotic optical properties including natural decay rate suppression and circular polarization engineering, should be within reach in the near future.
Modern quantum nanophotonics is revealed as the unique synergy between the quantum world and nanophotonics providing us with novel ways of controlling the quantum states of light, and enabling novel routes towards the realisation of future generation’s quantum information processing (QIP) systems. Focusing on the quantum photon-matter interaction, nano-confined light, nano-optical quantum interference and the control of linear and nonlinear quantum phenomena at the nanoscale in terms of the quantum superposition and entanglement, we provide a fundamental description of nano-photonic quantum systems. In particular, deep discussions on the outstanding characteristics of nano-structured photonic circuits are essential to understand the strong light-matter coupling, capable of boosting the coherence times and the processing efficiency of qubits, i.e., the basic building blocks of quantum computing. Furthermore, a progressive approach dealing with the QIP functionalities within concepts of quantum communication networks and powerful quantum computational architectures is provided, motivating an empirical hunt for efficient QIP approaches. Positive perspectives are given on the potential implications of modern quantum nanophotonics to the theoretical frameworks of the field.