Using matter wave interferometry to perform high precision measurements is an exciting field of modern day physics and engineering. Physical constants and anomalies too small to observe with classical devices can be probed and measured with quantum technology. The ability to control the wave nature of a specific particle opens up a vast set of methodologies engineered for the given particle. The most complete toolboxes exist for alkali metals such as rubidium and cesium. The atomic structure of strontium provides a number of advantages in further developing these methods and technologies, especially in the resolution of spectroscopic measurements.A promising method of matter-wave control utilizes optical waveguides and atomic properties to trap and guide matter waves. Using laser cooling techniques, atoms are cooled to microkelvin temperatures before being loaded onto the nanophotonic chip, thus receiving the appropriate name, atom-on-chip devices. The ability to manufacture the photonic waveguides in a multitude of different arrangements shows promise in being able to develop atomtronic devices which are equivalent to electronic devices, but utilize matter-waves of neutral atoms instead of electrons.The heart of our novel technology is an ultra-high vacuum (UHV) apparatus with sample loading capabilities. In this thesis, I discuss the design and construction of the apparatus to provide quick turn over between loading nanophotonic devices and experimental trapping by separation of the main chamber from a load lock. The ultimate pressures in both reach $3.8\\times10^{-11}$ and below $1\\times10^{-11}$ Torr and initial trials were conducted with a 36-48 hour turn over between loading a chip at atmosphere, and inserting it into the UHV main chamber. These metrics beats other groups by an order of magnitude in pressure and others week-long loading time. Continual improvements are being made to further decrease this time.
Using matter wave interferometry to perform high precision measurements is an exciting field of modern day physics and engineering. Physical constants and anomalies too small to observe with classical devices can be probed and measured with quantum technology. The ability to control the wave nature of a specific particle opens up a vast set of methodologies engineered for the given particle. The most complete toolboxes exist for alkali metals such as rubidium and cesium. The atomic structure of strontium provides a number of advantages in further developing these methods and technologies, especially in the resolution of spectroscopic measurements.A promising method of matter-wave control utilizes optical waveguides and atomic properties to trap and guide matter waves. Using laser cooling techniques, atoms are cooled to microkelvin temperatures before being loaded onto the nanophotonic chip, thus receiving the appropriate name, atom-on-chip devices. The ability to manufacture the photonic waveguides in a multitude of different arrangements shows promise in being able to develop atomtronic devices which are equivalent to electronic devices, but utilize matter-waves of neutral atoms instead of electrons.The heart of our novel technology is an ultra-high vacuum (UHV) apparatus with sample loading capabilities. In this thesis, I discuss the design and construction of the apparatus to provide quick turn over between loading nanophotonic devices and experimental trapping by separation of the main chamber from a load lock. The ultimate pressures in both reach 3.8times10−11 and below 1times10−11 Torr and initial trials were conducted with a 36-48 hour turn over between loading a chip at atmosphere, and inserting it into the UHV main chamber. These metrics beats other groups by an order of magnitude in pressure and others week-long loading time. Continual improvements are being made to further decrease this time.
The confinement and control of atomic clouds, at temperatures measured in nanokelvin, has become a valuable tool for physicists. As a source of new physics, development of cooling techniques has led to innovative new ways to probe the nature of reality. Of particular note are experiments carried out on new and exotic states of matter such as the Bose-Einstein condensate, unseen before the advent of these techniques. Likewise, the potential for applications outside of the lab is extensive and encompasses navigation, timekeeping, quantum communication and quantum computing. Manipulating cold atoms in the presence of a so-called ‘atom chip’ (a millimetre-scale electronic device) is currently considered the future of miniaturising these experiments and measurements, but since they still require precisely locked and stabilised lasers and predominantly must take place in the ultra-high vacuum regime, quantum control relies on an extensive and well-established infrastructure of optics, electronics, vacuum chambers and pumps. This encumbrance has slowed down the transition from chip-in-a-lab experiments to lab-on-a-chip technologies. This thesis is an account of work carried out in the development of enabling technologies which will accelerate this transition, including details of prototype devices made using established semiconductor and MEMS planar fabrication techniques. The construction and testing of an apparatus for anodically and eutectically bonding die-scale samples in ultra-high vacuum is described, along with an analysis and characterisation of some of its products.
Ultracold atoms exquisitely controlled by lasers are the quantum foundation, particularly for sensing, timekeeping, and computing, of state-of-the-art quantum science and technology. However, the laboratory-scale infrastructure for such optical-atomic quantum apparatus rarely translates into commercial applications. A promising solution is miniaturizing the optical layouts onto a chip-scale device integrated with cold atoms inside a compact ultra-high vacuum (UHV) chamber. For prototyping purposes, however, rapidly loading or exchanging test photonic devices into a UHV chamber is limited by the evacuation time from atmospheric pressures to the optimal pressures for ultracold atoms of 1 × 10-11 Torr, a process that typically takes weeks or months without cryogenics. Here, we present a loadlock apparatus and loading procedure capable of venting, exchanging, and evacuating back to <1×10-11 Torr in under 24 h. Our system allows for rapid testing and benchmarking of various photonic devices with ultracold atoms.
This thesis describes and characterizes a setup to conduct experiments combining the fields of cold atoms and nanophotonics. Furthermore, a series of numerical simulations is employed to deepen of atom transport under experimentally realistic conditions. The study of cold atoms is usually fundamental in nature and a very clean approach to investigate the laws of physics. High purity samples of atoms are cooled down to millikelvins or microkelvins. The potential landscape for the atoms can be carefully controlled using lasers and/or magnetic fields. Since the atoms' responses to electric, magnetic or electromagnetic fields are known with very high fidelity, any deviations to the state the atoms are prepared in can be precisely measured. Nanophotonics is the study of light close to or beyond the diffraction limit. In this region the field-like nature of light starts to play a role. By confining light in sub-wavelength-sized structures, high peak intensities can be achieved, giving rise to exciting non-linear optics phenomena. The strong field gradient that can be created allows, for instance, precise spectroscopy measurements, phase-sensitive sub-wavelength microscopy, as well as producing highly receptive sensing devices. Combining cold atoms and nanophotonics creates strong synergy effects. It gives access to strong coupling of light and matter. The scalability of nanophotonics now extends to atomic physics. Atoms can be trapped, coupled and manipulated at very small length scales, and in large numbers. Moreover, the potential landscape for atoms is highly customizable. The rubidium isotope 87 is used in this setup. A cloud of rubidium atoms is gathered and cooled in a two dimensional magneto-optical trap (MOT). Since the atoms are only cooled in two dimensions, they are free to escape in the third dimension and load a following three dimensional MOT. The atoms are now cooled further, compressed and loaded into an optical dipole trap. This dipole trap transports the atoms close to a sample inside the vacuum chamber. A moving optical lattice, or optical conveyor belt, brings the atoms then close to the sample surface. Now experiments can be conducted, studying the interaction of cold atoms and strongly confined light. The atom transport down to the sample surface shows some unexpected behaviour: the atoms seem to spread through the optical lattice during transport. A combination of microscopic and macroscopic numerical simulations, including genetic algorithms, are used to deepen our understanding of the underlying physics. This also allows us to get access to experimental variables that cannot be directly obtained.
Casimir and Casimir-Polder effects are forces between electrically neutral bodies and particles in vacuum, arising entirely from quantum fluctuations. The modification to the vacuum electromagnetic-field modes imposed by the presence of any particle or surface can result in these mechanical forces, which are often the dominant interaction at small separations. These effects play an increasingly critical role in the operation of micro- and nano-mechanical systems as well as miniaturized atomic traps for precision sensors and quantum-information devices. Despite their fundamental importance, calculations present theoretical and numeric challenges, and precise atom-surface potential measurements are lacking in many geometric and distance regimes. \n \nThe spectroscopic measurement of Casimir-Polder-induced energy level shifts in optical-lattice trapped atoms offers a new experimental method to probe atom-surface interactions. Strontium, the current front-runner among optical frequency metrology systems, has demonstrated characteristics ideal for such precision measurements. An alkaline earth atom possessing ultra-narrow intercombination transitions, strontium can be loaded into an optical lattice at the “magic” wavelength where the probe transition is unperturbed by the trap light. Translation of the lattice will permit controlled transport of tightly-confined atomic samples to well-calibrated atom- surface separations, while optical transition shifts serve as a direct probe of the Casimir-Polder potential. \n \nWe have constructed a strontium magneto-optical trap (MOT) for future Casimir-Polder experiments. This thesis will describe the strontium apparatus, initial trap performance, and some details of the proposed measurement procedure.
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.
In modern quantum technology, different quantum systems have properties that make them effective for some tasks and less beneficial for others. Integrating these systems together into a single quantum hybrid system, exploiting the advantages of each systems strengths while suppressing their disadvantages, can advance the total performance. On-chip quantum hybrid systems coupled to an ensemble of ultracold atoms show a great potential for advancing quantum technology, because they combine the long coherence time of the atomic ensemble with access to conventional read-out techniques provided by the chip. This thesis presents an apparatus that we have built to carry out experiments with coupling ultracold 87Rb gases to various systems, including nanomechanics and optical cavities. The apparatus operates at ultra-high vacuum conditions, required for experiments with ultracold gases, and its design allows us to easily and quickly switch between different on-chip devices to perform and study quantum hybridization with ultracold gases. Such versatility is provided by separating the region where the ultracold gas is created from the location of the chip, and implementing a system which can optically transfer the atoms between these two regions. In this work we also describe atom cooling techniques used in this experiment, including magneto-optical trapping, sub-Doppler cooling in optical molasses and evaporative cooling. These methods have demonstrated cooling to temperatures below 100 uK. We also discuss a setup for optimal optical-dipole transport. Finally, we theoretically consider magnetic coupling between atoms and nanomechanical oscillators and propose using the Landau-Zener transitions as a method for reducing or measuring mechanical temperature of the resonators, and to create quantum entanglement between multiple devices.