51 research outputs found
Demonstration of integrated microscale optics in surface-electrode ion traps
In ion trap quantum information processing, efficient fluorescence collection
is critical for fast, high-fidelity qubit detection and ion-photon
entanglement. The expected size of future many-ion processors require scalable
light collection systems. We report on the development and testing of a
microfabricated surface-electrode ion trap with an integrated high numerical
aperture (NA) micromirror for fluorescence collection. When coupled to a low NA
lens, the optical system is inherently scalable to large arrays of mirrors in a
single device. We demonstrate stable trapping and transport of 40Ca+ ions over
a 0.63 NA micromirror and observe a factor of 1.9 enhancement in photon
collection compared to the planar region of the trap.Comment: 15 pages, 8 figure
Controlling trapping potentials and stray electric fields in a microfabricated ion trap through design and compensation
Recent advances in quantum information processing with trapped ions have
demonstrated the need for new ion trap architectures capable of holding and
manipulating chains of many (>10) ions. Here we present the design and detailed
characterization of a new linear trap, microfabricated with scalable
complementary metal-oxide-semiconductor (CMOS) techniques, that is well-suited
to this challenge. Forty-four individually controlled DC electrodes provide the
many degrees of freedom required to construct anharmonic potential wells,
shuttle ions, merge and split ion chains, precisely tune secular mode
frequencies, and adjust the orientation of trap axes. Microfabricated
capacitors on DC electrodes suppress radio-frequency pickup and excess
micromotion, while a top-level ground layer simplifies modeling of electric
fields and protects trap structures underneath. A localized aperture in the
substrate provides access to the trapping region from an oven below, permitting
deterministic loading of particular isotopic/elemental sequences via
species-selective photoionization. The shapes of the aperture and
radio-frequency electrodes are optimized to minimize perturbation of the
trapping pseudopotential. Laboratory experiments verify simulated potentials
and characterize trapping lifetimes, stray electric fields, and ion heating
rates, while measurement and cancellation of spatially-varying stray electric
fields permits the formation of nearly-equally spaced ion chains.Comment: 17 pages (including references), 7 figure
cis-Acting Complex-Trait-Associated lincRNA Expression Correlates with Modulation of Chromosomal Architecture.
Intergenic long noncoding RNAs (lincRNAs) are the largest class of transcripts in the human genome. Although many have recently been linked to complex human traits, the underlying mechanisms for most of these transcripts remain undetermined. We investigated the regulatory roles of a high-confidence and reproducible set of 69 trait-relevant lincRNAs (TR-lincRNAs) in human lymphoblastoid cells whose biological relevance is supported by their evolutionary conservation during recent human history and genetic interactions with other trait-associated loci. Their enrichment in enhancer-like chromatin signatures, interactions with nearby trait-relevant protein-coding loci, and preferential location at topologically associated domain (TAD) boundaries provide evidence that TR-lincRNAs likely regulate proximal trait-relevant gene expression in cis by modulating local chromosomal architecture. This is consistent with the positive and significant correlation found between TR-lincRNA abundance and intra-TAD DNA-DNA contacts. Our results provide insights into the molecular mode of action by which TR-lincRNAs contribute to complex human traits
Spatially uniform single-qubit gate operations with near-field microwaves and composite pulse compensation
We present a microfabricated surface-electrode ion trap with a pair of
integrated waveguides that generate a standing microwave field resonant with
the 171Yb+ hyperfine qubit. The waveguides are engineered to position the wave
antinode near the center of the trap, resulting in maximum field amplitude and
uniformity along the trap axis. By calibrating the relative amplitudes and
phases of the waveguide currents, we can control the polarization of the
microwave field to reduce off-resonant coupling to undesired Zeeman sublevels.
We demonstrate single-qubit pi-rotations as fast as 1 us with less than 6 %
variation in Rabi frequency over an 800 um microwave interaction region. Fully
compensating pulse sequences further improve the uniformity of X-gates across
this interaction region.Comment: 14 pages, 8 figure
The Buffer Gas Beam: An Intense, Cold, and Slow Source for Atoms and Molecules
Beams of atoms and molecules are stalwart tools for spectroscopy and studies
of collisional processes. The supersonic expansion technique can create cold
beams of many species of atoms and molecules. However, the resulting beam is
typically moving at a speed of 300-600 m/s in the lab frame, and for a large
class of species has insufficient flux (i.e. brightness) for important
applications. In contrast, buffer gas beams can be a superior method in many
cases, producing cold and relatively slow molecules in the lab frame with high
brightness and great versatility. There are basic differences between
supersonic and buffer gas cooled beams regarding particular technological
advantages and constraints. At present, it is clear that not all of the
possible variations on the buffer gas method have been studied. In this review,
we will present a survey of the current state of the art in buffer gas beams,
and explore some of the possible future directions that these new methods might
take
A high-precision rf trap with minimized micromotion for an In+ multiple-ion clock
We present an experiment to characterize our new linear ion trap designed for
the operation of a many-ion optical clock using 115-In^+ as clock ions. For the
characterization of the trap as well as the sympathetic cooling of the clock
ions we use 172-Yb^+. The trap design has been derived from finite element
method (FEM) calculations and a first prototype based on glass-reinforced
thermoset laminates was built. This paper details on the trap manufacturing
process and micromotion measurement. Excess micromotion is measured using
photon-correlation spectroscopy with a resolution of 1.1nm in motional
amplitude, and residual axial rf fields in this trap are compared to FEM
calculations. With this method, we demonstrate a sensitivity to systematic
clock shifts due to excess micromotion of |({\Delta}{\nu}/{\nu})| = 8.5x10^-20.
Based on the measurement of axial rf fields of our trap, we estimate a number
of twelve ions that can be stored per trapping segment and used as an optical
frequency standard with a fractional inaccuracy of \leq 1x10^-18 due to
micromotion.Comment: 19 pages with 14 picture
Limitations of PCR detection of filarial DNA in human stools from subjects non-infected with soil-transmitted helminths
The standard techniques for diagnosis of human filariasis are the microscopic examination of blood smears or skin biopsies, which are relatively invasive and poorly sensitive at low levels of infection. Recently, filarial DNA has been detected in fecal samples from non-human primates in Central Africa. The aim of this study was to demonstrate proof-of-concept of a non-invasive molecular diagnosis technique for human filariasis by targeting fragments of 12S rDNA, Cox1, ITS1 and LL20-15kDa ladder antigen-gene by conventional PCR in DNA extracted from stool samples of 52 people infected with Mansonella perstans and/or Loa loa. Of these, 10 patients were infected with soil-transmitted helminths (Trichuris trichiura and/or Ascaris lumbricoides), and none were positive for Necator americanus. Interestingly, no filarial gene fragments were detected in the stools of any of the 52 patients. Future studies should evaluate whether a co-infection with soil-transmitted helminths causing gastrointestinal bleeding and likely allowing (micro)filaria exit into the digestive tract, may facilitate the molecular detection of filarial DNA fragments in stool samples
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