Single atom interferometers and Bloch oscillations in quantum walks

The deliberate coherent manipulation of a single atom's spin and position in an optical lattice has great potential as a primitive for future quantum simulators. This thesis investigates position control on ultracold Caesium atoms by modulating the polarization of light in a state-selective optical lattice, allowing us to explore matter wave interference along flexible, digitally programmable trajectories. The effects on coherence and phase are explored in depth using atom interferometry; this is also used to demonstrate measurements of optical and inertial potential gradients. By performing a quantum walk in an inertial gradient, a quantum simulation of Bloch oscillations in an electric field could be run, showing the hallmark oscillations in the walk distribution width. We also investigate Landau-Zener tunneling in the quantum walk at extremely high strengths of the virtual electric field

Cold-Atom Loading of Hollow-Core Photonic Crystal Fibre for Quantum Technologies

Ultra-strong light-atom interaction is a key resource for numerous applications in quantum-information processing, nonlinear optics, and quantum sensing. Maximising the strength of the interaction requires optimising the combination of light-atom coherent interaction time, spatial overlap between the optical mode and the atomic cross section, and the number of participating atoms. An exciting approach to achieving these goals is to use a collection of laser-cooled atoms inside a hollow-core photonic crystal fibre. Here the tight transverse confinement provided by fibre guarantees overlap between the atomic sample and guided optical modes over an arbitrarily long distance. Laser cooling improves the effective atom number of the sample by increasing the fraction that participate in the interaction and significantly improves the coherent interaction time by reducing the spatial decoherence rate of the ensemble. This project focuses around the development of an apparatus that realises the lasercooling, trapping, and loading of atoms into a kagome-lattice hollow-core fibre. In this thesis we describe the development of the elements required to realise this task, including the vacuum system, laser sources, computer oversight, and theoretical models employed. The resulting platform is capable of achieving the ultra-high optical depths required for exciting quantum-optics applications such as long-lived coherent optical pulse storage. We have demonstrated high-efficiency transport of cold rubidium atoms from a magneto-optical trap into a hollow-core fibre, measuring a peak optical depth of 600 with only 3£106 atoms. These experiments were guided by a Monte-Carlo simulation that has been shown to have excellent agreement with the physical system. The results show that this platform is in an excellent position to investigate coherent optical phenomena at the few-photon level. Along the way we investigated the application of light-shift engineering to both measure and compensate for the perturbative effects the strong light fields present in the experiment have on atomic states. We extend the ‘magic-wavelength’ technique used in the atomic lattice clock community to nullify the lineshape broadening of the target ensemble by introducing an additional light field. This allows the technique to be implemented in a broad range of atomic species and transitions, where the original technique was only accessible for limited species with specific energy-level structures. We also take advantage of light-shift engineering to extract a detailed model of the spatial distribution of an optically-trapped ensemble through a simple spectroscopic technique. We use this model to infer the temperature, coherence time, and number of atoms in the trap in addition to the depth of the trap itself. Experimentally we demonstrate this on our cold-atom-filled fibre platform, showing that this information can be extracted from a system with limited optical access and where conventional techniques cannot be applied. The apparatus and experimental techniques we have developed place this project in an excellent position to perform cutting-edge research in the fields of quantum information processing and nonlinear optics.Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 202

A COLLISION AVOIDANCE SYSTEM FOR AUTONOMOUS UNDERWATER VEHICLES

The work in this thesis is concerned with the development of a novel and practical collision avoidance system for autonomous underwater vehicles (AUVs). Synergistically, advanced stochastic motion planning methods, dynamics quantisation approaches, multivariable tracking controller designs, sonar data processing and workspace representation, are combined to enhance significantly the survivability of modern AUVs. The recent proliferation of autonomous AUV deployments for various missions such as seafloor surveying, scientific data gathering and mine hunting has demanded a substantial increase in vehicle autonomy. One matching requirement of such missions is to allow all the AUV to navigate safely in a dynamic and unstructured environment. Therefore, it is vital that a robust and effective collision avoidance system should be forthcoming in order to preserve the structural integrity of the vehicle whilst simultaneously increasing its autonomy. This thesis not only provides a holistic framework but also an arsenal of computational techniques in the design of a collision avoidance system for AUVs. The design of an obstacle avoidance system is first addressed. The core paradigm is the application of the Rapidly-exploring Random Tree (RRT) algorithm and the newly developed version for use as a motion planning tool. Later, this technique is merged with the Manoeuvre Automaton (MA) representation to address the inherent disadvantages of the RRT. A novel multi-node version which can also address time varying final state is suggested. Clearly, the reference trajectory generated by the aforementioned embedded planner must be tracked. Hence, the feasibility of employing the linear quadratic regulator (LQG) and the nonlinear kinematic based state-dependent Ricatti equation (SDRE) controller as trajectory trackers are explored. The obstacle detection module, which comprises of sonar processing and workspace representation submodules, is developed and tested on actual sonar data acquired in a sea-trial via a prototype forward looking sonar (AT500). The sonar processing techniques applied are fundamentally derived from the image processing perspective. Likewise, a novel occupancy grid using nonlinear function is proposed for the workspace representation of the AUV. Results are presented that demonstrate the ability of an AUV to navigate a complex environment. To the author's knowledge, it is the first time the above newly developed methodologies have been applied to an A UV collision avoidance system, and, therefore, it is considered that the work constitutes a contribution of knowledge in this area of work.J&S MARINE LT

Designing sound : procedural audio research based on the book by Andy Farnell

In procedural media, data normally acquired by measuring something, commonly described as sampling, is replaced by a set of computational rules (procedure) that defines the typical structure and/or behaviour of that thing. Here, a general approach to sound as a definable process, rather than a recording, is developed. By analysis of their physical and perceptual qualities, natural objects or processes that produce sound are modelled by digital Sounding Objects for use in arts and entertainments. This Thesis discusses different aspects of Procedural Audio introducing several new approaches and solutions to this emerging field of Sound Design.Em Media Procedimental, os dados os dados normalmente adquiridos através da medição de algo habitualmente designado como amostragem, são substituídos por um conjunto de regras computacionais (procedimento) que definem a estrutura típica, ou comportamento, desse elemento. Neste caso é desenvolvida uma abordagem ao som definível como um procedimento em vez de uma gravação. Através da análise das suas características físicas e perceptuais , objetos naturais ou processos que produzem som, são modelados como objetos sonoros digitais para utilização nas Artes e Entretenimento. Nesta Tese são discutidos diferentes aspectos de Áudio Procedimental, sendo introduzidas várias novas abordagens e soluções para o campo emergente do Design Sonoro

Cumulative index to NASA Tech Briefs, 1963-1967

Cumulative index to NASA survey on technology utilization of aerospace research outpu

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion