In-vacuum active electronics for microfabricated ion traps.

The advent of microfabricated ion traps for the quantum information community has allowed research groups to build traps that incorporate an unprecedented number of trapping zones. However, as device complexity has grown, the number of digital-to-analog converter (DAC) channels needed to control these devices has grown as well, with some of the largest trap assemblies now requiring nearly one hundred DAC channels. Providing electrical connections for these channels into a vacuum chamber can be bulky and difficult to scale beyond the current numbers of trap electrodes. This paper reports on the development and testing of an in-vacuum DAC system that uses only 9 vacuum feedthrough connections to control a 78-electrode microfabricated ion trap. The system is characterized by trapping single and multiple (40)Ca(+) ions. The measured axial mode stability, ion heating rates, and transport fidelities for a trapped ion are comparable to systems with external (air-side) commercial DACs.

Optical transmission through double-layer, laterally shifted metallic subwavelength hole arrays.

We measure the transmission of IR radiation through double-layer metal films with periodic arrays of subwavelength holes. When the two metal films are placed in sufficiently close proximity, two types of transmission resonances emerge. For the surface plasmon mode, the electromagnetic field is concentrated on the outer surface of the entire metallic layer stack. In contrast, for the guided mode, the field is confined to the gap between the two metal layers. Our measurements indicate that, as the two layers are laterally shifted from perfect alignment, the peak transmission frequency of the guided mode decreases significantly, while that of the surface plasmon mode remains largely unchanged, in agreement with numerical calculations.

Multiscale optics for enhanced light collection from a point source.

High-efficiency collection of photons emitted by a point source over a wide field of view (FoV) is crucial for many applications. Multiscale optics offer improved light collection by utilizing small optical components placed close to the optical source, while maintaining a wide FoV provided by conventional imaging optics. In this work, we demonstrate collection efficiency of 26% of photons emitted by a pointlike source using a micromirror fabricated in silicon with no significant decrease in collection efficiency over a 10 mm object space.

Casimir force on a surface with shallow nanoscale corrugations: geometry and finite conductivity effects.

We measure the Casimir force between a gold sphere and a silicon plate with nanoscale, rectangular corrugations with a depth comparable to the separation between the surfaces. In the proximity force approximation (PFA), both the top and bottom surfaces of the corrugations contribute to the force, leading to a distance dependence that is distinct from a flat surface. The measured Casimir force is found to deviate from the PFA by up to 10%, in good agreement with calculations based on scattering theory that includes both geometry effects and the optical properties of the material.

Measurement of the Casimir force between a gold sphere and a silicon surface with nanoscale trench arrays.

We report measurements of the Casimir force between a gold sphere and a silicon surface with an array of nanoscale, rectangular corrugations using a micromechanical torsional oscillator. At distances between 150 and 500 nm, the measured force shows significant deviations from the pairwise additive formulism, demonstrating the strong dependence of the Casimir force on the shape of the interacting bodies. The observed deviation, however, is smaller than the calculated values for perfectly conducting surfaces, possibly due to the interplay between finite conductivity and geometry effects.

Controlling the phase delay of light transmitted through double-layer metallic subwavelength slit arrays.

We demonstrate that the phase of light transmitted through double-layer subwavelength metallic slit arrays can be controlled through lateral shift of the two layers. Our samples consist of two aluminum layers, each of which contains an array of subwavelength slits. The two layers are placed in sufficient proximity to allow coupling of the evanescent fields at resonance. By changing the lateral shift between the layers from zero to half the period, the phase of the transmitted electromagnetic field is increased by pi, while the transmitted intensity remains high. Such a controllable phase delay could open new capabilities for nanophotonic devices that cannot be achieved with single-layer structures.

Microfabricated quadrupole ion trap for mass spectrometer applications.

An array of miniaturized cylindrical quadrupole ion traps, with a radius of 20 microm, is fabricated using silicon micromachining using phosphorus doped polysilicon and silicon dioxide for the purpose of creating a mass spectrometer on a chip. We have operated the array for mass-selective ion ejection and mass analysis using Xe ions at a pressure of 10(-4). The scaling rules for the ion trap in relation to operating pressure, voltage, and frequency are examined.

Optical transmission through double-layer metallic subwavelength slit arrays.

We present measurements of transmission of infrared radiation through double-layer metallic grating structures. Each metal layer contains an array of subwavelength slits and supports transmission resonance in the absence of the other layer. The two metal layers are fabricated in close proximity to allow coupling of the evanescent field on individual layers. The transmission of the double layer is found to be surprisingly large at particular wavelengths, even when no direct line of sight exists through the structure as a result of the lateral shifts between the two layers. We perform numerical simulations using rigorous coupled wave analysis to explain the strong dependence of the peak transmission on the lateral shift between the metal layers.

Production of lytic enzyme from Pseudomonas aeruginosa M-1001.

Pseudomonas aeruginosa M-1001 produced both hen-egg-white lysozyme inhibitors and lytic enzyme in the culture broth. The lytic enzyme produced was not inhibited by the lysozyme inhibitors. Maximal lytic activity was obtained when the strain was grown aerobically in a medium consisting of 0.25% glucose, 0.75% soluble strach, 0.25% beef extract, 0.25% Polypepton, 0.25% sodium L-glutamate and 0.0001% NaCl (pH 6), at 37 degrees C after 36 hrs. The lytic enzyme was stable at pH from 6 to 8 and temperatures below 40 degrees C. Many bacteria and Saccharomyces cerevisiae were found to be inhibited by the crude lytic enzyme produced from the M-1001 strain except for the strain itself and a few other microorganisms.

Production, purification and characterization of two proteinaceous hen-egg-white lysozyme inhibitors from Pseudomonas aeruginosa M-1001.

Two proteinaceous lysozyme inhibitors, hen-egg-white lysozyme inhibitors F-I and F-II, were isolated from the culture broth of a bacterial strain identified as Pseudomonas aeruginosa M-1001. Maximum lysozyme inhibitory activity was obtained when the bacterium was grown aerobically in a medium consisting of 0.25% glucose, 0.25% beef extract, 0.25% polypepton, 1.0% sodium L-glutamate, and 1.0% soluble starch (pH 7.0) at 37 degrees C after 20-24 hrs. F-I and F-II were purified 20 and 7.5-fold, respectively, from the culture supernatant of P. aeruginosa M-1001 by ammonium sulfate fractionation, DEAE-Sepharose CL-6B column chromatography, and Sephacryl S-200 gel chromatography. The molecular weights of F-I and F-II were estimated to be about 57,000 and 33,000, by SDS-PAGE, respectively. F-I was stable in a pH range between 6 and 10 and below 50 degrees C. F-II was stable in a pH range between 6 and 11 and below 40 degrees C. Many Gram-positive bacteria were found to be inhibited by the crude lysozyme inhibitors.