Light Trap Manipulation and Its Potential Use in Quantum Computing

During winter quarter 2007, the light polarization dependence of light traps used in quantum computing was researched. Throughout the quarter, a Mathematica program that simulates the trapping potential of light traps was modified; it now takes into account the polarization of light used, as well as the internal state of atoms used in the light traps. The goal for the next quarter, spring 2007, was to use the program that was generated to simulate the trapping potentials of varying parameters. This research was conducted to deduce whether there is any possible way to implement the light polarization dependence of light traps in quantum computing. More specifically, the intent was to investigate potential ways to create a two-qubit gate using the light polarization dependence of the light traps

One- and Two-Dimensional Optical Lattices on a Chip for Quantum Computing

We propose a way to make arrays of optical frequency dipole-force microtraps for cold atoms above a dielectric substrate. Traps are nodes in the evanescent wave fields above an optical waveguide resulting from interference of different waveguide modes. The traps have features sought in developing neutral atom based architectures for quantum computing: ∼1 mW of laser power yields very tight traps 150 nm above a waveguide with trap vibrational frequencies ∼1 MHz and vibrational ground state sizes ∼10 nm. The arrays are scalable and allow addressing of individual sites for quantum logic operations

Zwischen Ingenieurstudium und Lehramtsoption - Wann und warum entscheiden sich Studierende für den „PLan C“?

Da die Gewinnung von qualifizierten sowie geeigneten Lehrkräften für den gewerblich-technischen Bereich der berufsbildenden Schulen ein dauerhaftes Problem darstellt, wird in dem Beitrag der Frage nachgegangen, welche Gründe der Rekrutierungsproblematik zu Grunde liegen. Dafür werden Ergebnisse aus dem Projekt „PLan C“ vorgestellt, die das Potential der ingenieurwissenschaftlichen Studierenden, als potentielle Zielgruppe für die Rekrutierung lehramtsinteressierter Personen untersucht. Es zeigt sich, dass sich innerhalb der anvisierten Zielgruppe lehramtsinteressierte Studierende befinden, die einen inhaltlich begründeten Wechsel vom Ingenieursstudium in das berufsbildende Lehramt vollzogen haben, jedoch handelt es sich hierbei nur um eine geringe Anzahl.Schlüsselwörter: Gewerblich-Technisches Lehramt, Rekrutierungsproblematik, Zielgruppen im Lehramt, Lehrkräftemangel, Studiengangswechsel___________Between the engineering major and becoming a teacher: When and why do students choose PLan C?Since the acquisition of qualified and capable teachers for the commercial- technical subjects of vocational schooling remains an enduring problem, this contribution inquires into the reasons that lie at the foundation of the recruitment problem. To this end, results from the project “PLan C“ are presented, the aim of which is to examine the potential in targeting engineering students for recruitment as vocational educators. It is apparent that within this target group there are students interested in pursuing vocational teacher education who have made a justified shift from an engineering degree to one in vocational education, yet the number of such students remains relatively low.Keywords: commercial- technical teacher education, recruitment problem, target groups in teacher education, teacher shortage, degree chang

Projection of Diffraction Patterns for Use in Cold-Neutral-Atom Trapping

Scalar diffraction theory is combined with beam-propagation techniques to investigate the projection of near-field diffraction patterns to spatial locations away from the aperture for use in optically trapping cold neutral alkali-metal atoms. Calculations show that intensity distributions with localized bright and dark spots usually found within a millimeter of the diffracting aperture can be projected to a region free from optical components such as a cloud of cold atoms within a vacuum chamber. Calculations also predict that the critical properties of the optical dipole atom traps are not only maintained for the projected intensity patterns but also can be manipulated and improved by adjustment of the optical components outside the vacuum chamber

Polarization-Dependent Atomic Dipole Traps Behind a Circular Aperture for Neutral-Atom Quantum Computing

The neutral-atom quantum computing community has successfully implemented almost all necessary steps for constructing a neutral-atom quantum computer. We present computational results of a study aimed at solving the remaining problem of creating a quantum memory with individually addressable sites for quantum computing. The basis of this quantum memory is the diffraction pattern formed by laser light incident on a circular aperture. Very close to the aperture, the diffraction pattern has localized bright and dark spots that can serve as red-detuned or blue-detuned atomic dipole traps. These traps are suitable for quantum computing even for moderate laser powers. In particular, for moderate laser intensities (~100 W/cm2) and comparatively small detunings (~1000–10 000 linewidths), trap depths of ~1 mK and trap frequencies of several to tens of kilohertz are achieved. Our results indicate that these dipole traps can be moved by tilting the incident laser beams without significantly changing the trap properties. We also explored the polarization dependence of these dipole traps. We developed a code that calculates the trapping potential energy for any magnetic substate of any hyperfine ground state of any alkali-metal atom for any laser detuning much smaller than the fine-structure splitting for any given electric field distribution. We describe details of our calculations and include a summary of different notations and conventions for the reduced matrix element and how to convert it to SI units. We applied this code to these traps and found a method for bringing two traps together and apart controllably without expelling the atoms from the trap and without significant tunneling probability between the traps. This approach can be scaled up to a two-dimensional array of many pinholes, forming a quantum memory with single-site addressability, in which pairs of atoms can be brought together and apart for two-qubit gates for quantum computing

Optical Dipole Traps for Cold Atoms using Diffracted Laser Light

We theoretically investigate the feasibility of using intensity distributions of light of a single laser beam diffracted by a circular aperture as optical dipole traps for cold neutral atoms. Localized and cylindrically symmetric traps on the central axis of the circular aperture exist for both blue- and red-detuned laser light. Experimental mapping of the spots of interest using CO2 laser light demonstrates the existence of these light distributions for laboratory conditions and their agreement with theoretical predictions

Light propagation in linear optical media

Light Propagation in Linear Optical Media describes light propagation in linear media by expanding on diffraction theories beyond what is available in classic optics books. In one volume, this book combines the treatment of light propagation through various media, interfaces, and apertures using scalar and vector diffraction theories. After covering the fundamentals of light and physical optics, the authors discuss light traveling within an anisotropic crystal and present mathematical models for light propagation across planar boundaries between different media. They describe the propagation

Two-Dimensional Imaging of Neutral Alkali Atom Samples Using Surface Ionization

We describe the design and characterization of a high resolution, high efficiency detector for two-dimensional imaging of neutral atoms. Incident atoms are surface-ionized by a tungsten-coated hot ribbon and the resulting ions are accelerated into a microchannel plate detector with a phosphor screen output. With this design we can detect individual alkali and other low ionization potential atoms and molecules with a spatial resolution of ∼ 20 μm. We find backgrounds on the order of 30 Hz over an active detection region of 20 mm2, a time response of ⩽ 1/30 s, and a detection efficiency of ∼ 50%. This detector can be used to image cold as well as thermal atomic or molecular beams