Zero-Point cooling and low heating of trapped 111Cd+ ions

We report on ground state laser cooling of single 111Cd+ ions confined in radio-frequency (Paul) traps. Heating rates of trapped ion motion are measured for two different trapping geometries and electrode materials, where no effort was made to shield the electrodes from the atomic Cd source. The low measured heating rates suggest that trapped 111Cd+ ions may be well-suited for experiments involving quantum control of atomic motion, including applications in quantum information science.Comment: 4 pages, 6 figures, Submitted to PR

The bloodstream differentiation - division of Trypanosoma brucei studied using mitochondrial markers

In the bloodstream of its mammalian host, the African trypanosome Trypanosoma brucei undergoes a life cycle stage differentiation from a long, slender form to a short, stumpy form. This involves three known major events: exit from a proliferative cell cycle, morphological change and mitochondrial biogenesis. Previously, models have been proposed accounting for these events (Matthews & Gull 1994a). Refinement of, and discrimination between, these models has been hindered by a lack of stage-regulated antigens useful as markers at the single-cell level. We have now evaluated a variety of cytological markers and applied them to investigate the coordination of phenotypic differentiation and cell cycle arrest. Our studies have focused on the differential expression of the mitochondrial enzyme dihydrolipoamide dehydrogenase relative to the differentiation-division of bloodstream trypanosomes. The results implicate a temporal order of events: commitment, division, phenotypic differentiation

Implementation of Grover's Quantum Search Algorithm in a Scalable System

We report the implementation of Grover's quantum search algorithm in the scalable system of trapped atomic ion quantum bits. Any one of four possible states of a two-qubit memory is marked, and following a single query of the search space, the marked element is successfully recovered with an average probability of 60(2)%. This exceeds the performance of any possible classical search algorithm, which can only succeed with a maximum average probability of 50%.Comment: 4 pages, 3 figures, updated error discussio

Entanglement of Trapped-Ion Clock States

A M{\o}lmer-S{\o}rensen entangling gate is realized for pairs of trapped $^{111}$Cd$^+$ ions using magnetic-field insensitive "clock" states and an implementation offering reduced sensitivity to optical phase drifts. The gate is used to generate the complete set of four entangled states, which are reconstructed and evaluated with quantum-state tomography. An average target-state fidelity of 0.79 is achieved, limited by available laser power and technical noise. The tomographic reconstruction of entangled states demonstrates universal quantum control of two ion-qubits, which through multiplexing can provide a route to scalable architectures for trapped-ion quantum computing.Comment: 6 pages, 5 figure

Magneto-optical Trapping of Cadmium

We report the laser-cooling and confinement of Cd atoms in a magneto-optical trap, and characterize the loading process from the background Cd vapor. The trapping laser drives the 1S0-1P1 transition at 229 nm in this two-electron atom and also photoionizes atoms directly from the 1P1 state. This photoionization overwhelms the other loss mechanisms and allows a direct measurement of the photoionization cross section, which we measure to be 2(1)x10^(-16)cm^(2) from the 1P1 state. When combined with nearby laser-cooled and trapped Cd^(+) ions, this apparatus could facilitate studies in ultracold interactions between atoms and ions.Comment: 8 pages, 11 figure

Telephone-Based Identification of Mild Cognitive Impairment and Dementia in a Multicultural Cohort

Background: Telephone-based interviews can be used for screening and to obtain key study outcomes when participants in longitudinal studies die or cannot be seen in person, but must be validated among ethnically and educationally diverse people. Objective: To determine the accuracy of a telephone interview in classifying (1) demented from nondemented participants, (2) cognitively impaired participants from cognitively normal participants, and (3) participants with mild cognitive impairment (MCI) from those with normal cognition or (4) MCI from dementia among an ethnically and educationally diverse community-based sample. Method: The sample consisted of 377 (30.5% non-Hispanic white, 34.7% non-Hispanic black, and 33.7% Caribbean Hispanic) older adults. The validation standard was diagnosis of dementia and MCI based on in-person evaluation. The Telephone Interview for Cognitive Status (TICS) and the Dementia Questionnaire (DQ) were administered within the same assessment wave. Results: The sample included 256 people (67.9%) with normal cognition, 68 (18.0%) with MCI, and 53 (14.1%) with dementia. Validity of the TICS was comparable among non-Hispanic whites, non-Hispanic blacks, and Hispanics. Among non-Hispanic whites, the DQ had better discrimination of those with dementia from those without dementia and from those with MCI than among other racial/ethnic groups. Telephone measures discriminated best when used to differentiate demented from nondemented participants (88% sensitivity and 87% specificity for the TICS; 66% sensitivity and 89% specificity for DQ) and when used to differentiate cognitively normal participants from those with cognitive impairment (ie, MCI and dementia combined; 73% sensitivity and 77% specificity for the TICS; 49% sensitivity and 82% specificity for DQ). When demographics and prior memory test performance were used to calculate pretest probability, consideration of the telephone measures significantly improved diagnostic validity. Conclusions: The TICS has high diagnostic validity for identification of dementia among ethnically diverse older adults, especially when supported by the DQ and prior visit data. However, telephone interview data were unable to reliably distinguish MCI from normal cognition

Phase Control of Trapped Ion Quantum Gates

There are several known schemes for entangling trapped ion quantum bits for large-scale quantum computation. Most are based on an interaction between the ions and external optical fields, coupling internal qubit states of trapped-ions to their Coulomb-coupled motion. In this paper, we examine the sensitivity of these motional gate schemes to phase fluctuations introduced through noisy external control fields, and suggest techniques to suppress the resulting phase decoherence.Comment: 21 pages 12 figure

Do Neuropsychological Tests Have the Same Meaning in Spanish Speakers as They Do in English Speakers?

OBJECTIVE: The purpose of this study was to examine whether neuropsychological tests translated into Spanish measure the same cognitive constructs as the original English versions. METHOD: Older adult participants (N = 2,664), who did not exhibit dementia from the Washington Heights Inwood Columbia Aging Project (WHICAP), a community-based cohort from northern Manhattan, were evaluated with a comprehensive neuropsychological battery. The study cohort includes both English (n = 1,800) and Spanish speakers (n = 864) evaluated in their language of preference. Invariance analyses were conducted across language groups on a structural equation model comprising four neuropsychological factors (memory, language, visual-spatial ability, and processing speed). RESULTS: The results of the analyses indicated that the four-factor model exhibited partial measurement invariance, demonstrated by invariant factor structure and factor loadings but nonequivalent observed score intercepts. CONCLUSION: The finding of invariant factor structure and factor loadings provides empirical evidence to support the implicit assumption that scores on neuropsychological tests are measuring equivalent psychological traits across these two language groups. At the structural level, the model exhibited invariant factor variances and covariances