Deterministic reordering of 40Ca+ ions in a linear segmented Paul trap

In the endeavour to scale up the number of qubits in an ion-based quantum computer several groups have started to develop miniaturized ion traps for extended spatial control and manipulation of the ions. Shuttling and separation of ion strings have been the foremost issues in linear-trap arrangements and some prototypes of junctions have been demonstrated for the extension of ion motion to two dimensions (2D). While junctions require complex trap structures, small extensions to the 1D motion can be accomplished in simple linear trap arrangements. Here, control of the extended field in a planar, linear chip trap is used to shuttle ions in 2D. With this approach, the order of ions in a string is deterministically reversed. Optimized potentials are theoretically derived and simulations show that the reordering can be carried out adiabatically. The control over individual ion positions in a linear trap presents a new tool for ion-trap quantum computing. The method is also expected to work with mixed crystals of different ion species and as such could have applications for sympathetic cooling of an ion string.Comment: 18 pages, 9 figures. Added section on possibility of adiabatic turn. Added appendix on point charge model. Other minor alterations/clarifications. Version now published (http://www.iop.org/EJ/abstract/1367-2630/11/10/103008

Trapped-ion probing of light-induced charging effects on dielectrics

We use a string of confined $^{40}$Ca$^+$ ions to measure perturbations to a trapping potential which are caused by light-induced charging of an anti-reflection coated window and of insulating patches on the ion-trap electrodes. The electric fields induced at the ions' position are characterised as a function of distance to the dielectric, and as a function of the incident optical power and wavelength. The measurement of the ion-string position is sensitive to as few as $40$ elementary charges per $\sqrt{\mathrm{Hz}}$ on the dielectric at distances of order millimetres, and perturbations are observed for illumination with light of wavelengths as long as 729\,nm. This has important implications for the future of miniaturised ion-trap experiments, notably with regards to the choice of electrode material, and the optics that must be integrated in the vicinity of the ion. The method presented can be readily applied to the investigation of charging effects beyond the context of ion trap experiments.Comment: 11 pages, 5 figure

Spatially-resolved potential measurement with ion crystals

We present a method to measure potentials over an extended region using one-dimensional ion crystals in a radio frequency (RF) ion trap. The equilibrium spacings of the ions within the crystal allow the determination of the external forces acting at each point. From this the overall potential, and also potentials due to specific trap features, are calculated. The method can be used to probe potentials near proximal objects in real time, and can be generalized to higher dimensions.Comment: 7 pages (double spaced), 3 figure

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

Optimum electrode configurations for fast ion separation in microfabricated surface ion traps

For many quantum information implementations with trapped ions, effective shuttling operations are important. Here we discuss the efficient separation and recombination of ions in surface ion trap geometries. The maximum speed of separation and recombination of trapped ions for adiabatic shuttling operations depends on the secular frequencies the trapped ion experiences in the process. Higher secular frequencies during the transportation processes can be achieved by optimising trap geometries. We show how two different arrangements of segmented static potential electrodes in surface ion traps can be optimised for fast ion separation or recombination processes. We also solve the equations of motion for the ion dynamics during the separation process and illustrate important considerations that need to be taken into account to make the process adiabatic

Ionic balances of forest soils reciprocally transplanted among sites with varying pollution inputs.

Forest ecosystems are currently being exposed to changes in chemical inputs and it is suggested that physical climate is also changing. A novel approach has been used to study the effects of ionic inputs and climatic conditions on forest soils by reciprocally exchanging lysimeters containing undisturbed soil columns between four forest sites in Europe. The soil columns contained no living roots and simulated a clear cut situation. The soils chosen represented different stages of acidification and were taken from sites along a transect of increasing exposure to acidic and nitrogen pollution. The purpose of the study was to quantify the reactions of soils when transferred to different environments. Element balances were used as an aggregated indicator to describe the reaction of the soil. The input of protons in local throughfall increased along the transect from 0.01 kmol h

Effects of air pollutant-temperature interactions on mineral-N dynamics and cation leaching in reciplicate forest soil transplantation experiments

Increased emissions of nitrogen compounds have led to atmospheric deposition to forest soils exceeding critical loads of N over large parts of Europe. To determine whether the chemistry of forest soils responds to changes in throughfall chemistry, intact soil columns were reciprocally transplanted between sites, with different physical conditions, across a gradient of N and S deposition in Europe. The transfer of a single soil to the various sites affected its net nitrification. This was not simply due to the nitrification of different levels of N deposition but was explained by differences in physical climates which influenced mineralization rates. Variation in the amount of net nitrification between soil types at a specific site were explained largely by soil pH. Within a site all soil types showed similar trends in net nitrification over time. Seasonal changes in net nitrification corresponds to oscillations in temperature but variable time lags had to be introduced to explain the relationships. With Arrhenius' law it was possible to approximate gross nitrification as a function of temperature. Gross nitrification equalled net nitrification after adaptation of the microbial community of transplanted soils to the new conditions. Time lags, and underestimates of gross nitrification in autumn, were assumed to be the result of increased NH4 + availability due either to changes in the relative rates of gross and net N transformations or to altered soil fauna-microbial interactions combined with improved moisture conditions. Losses of NO3/- were associated with Ca2+ and Mg2+ in non-acidified soil types and with losses of Al3+ in the acidified soils. For single soils the ion equilibrium equation of Gaines-Thomas provided a useful approximation of Al3+ concentrations in the soil solution as a function of the concentration of Ca2+. The between site deviations from this predicted equilibrium, which existed for single soils, could be explained by differences in throughfall chemistry which affected the total ionic strength of the soil solution. The approach of reciprocally transferring soil columns highlighted the importance of throughfall chemistry, interacting with the effect of changes in physical climate on forest soil acidification through internal proton production, in determining soil solution chemistry. A framework outlining the etiology of forest die-back induced by nitrogen saturation is proposed

Transcriptional landscape of trans-kingdom communication between Candida albicans and Streptococcus gordonii

Recent studies have shown that the transcriptional landscape of the pleiomorphic fungus Candida albicans is highly dependent upon growth conditions. Here using a dual RNA-seq approach we identified 299 C. albicans and 72 Streptococcus gordonii genes that were either up- or down-regulated specifically as a result of co-culturing these human oral cavity microorganisms. Seventy five C. albicans genes involved in responses to chemical stimuli, regulation, homeostasis, protein modification and cell cycle were statistically (P ≤0.05) up-regulated, while 36 genes mainly involved in transport and translation were down-regulated. Up-regulation of filamentation-associated TEC1 and FGR42 genes, and of ALS1 adhesin gene, concurred with previous evidence that the C. albicans yeast to hypha transition is promoted by S. gordonii. Increased expression of genes required for arginine biosynthesis in C. albicans was potentially indicative of a novel oxidative stress response. The transcriptional response of S. gordonii to C. albicans was less dramatic, with only eight S. gordonii genes significantly (P ≤0.05) up-regulated ≥ twofold (glpK, rplO, celB, rplN, rplB, rpsE, ciaR, and gat). The expression patterns suggest that signals from S. gordonii cause a positive filamentation response in C. albicans, while S. gordonii appears to be transcriptionally less influenced by C. albicans

Axenic culture of a candidate division TM7 bacterium from the human oral cavity and biofilm interactions with other oral bacteria

Taken by U.S. Army medic Charles Tweel in 1971, this photograph shows Rusty Hide (far left) and two other Americans at Camp Evans during the Vietnam War. This photograph is part of the Charles Tweel Collection (AV 324) at the Ohio History Connection. Charles Tweel grew up in Columbus, Ohio, and attended The Ohio State University. After graduation in 1968, he enlisted in the U.S. Army as a non-combatant, first training as a medic at Fort Sam Huston, followed by nine months of additional training at Valley Forge General Hospital in Phoenixville, Pennsylvania. He finished his training as a Specialist 3 and 91C, MOS, and went on to serve in Bamberg, Germany, with combat engineers for one year. In January 1971, Tweel served in Vietnam with the Headquarters and Headquarters Company, 2nd Battalion (Air Mobile), 506th Infantry Regiment, 101st Airborne Division, based out of Camp Evans near Phu Bai, north of Hue, until December of that year. Tweel spent most of his service on various firebases as the medic in charge, and occasionally shared firebases with South Vietnamese soldiers. He also visited MedCAP stations (Medical Civic Action Programs) where he treated civilians. Tweel received the Bronze Star Medal for meritorious achievement, and was promoted to Specialist 5 in 1971. After discharge from the Army, he went to medical school and was in private practice as a family practitioner from 1979-2016, and now works part-time in inner city medical clinics in Columbus, Ohio, and Charleston, South Carolina

Axenic culture of a candidate division TM7 bacterium from the human oral cavity and biofilm interactions with other oral bacteria

The diversity of bacterial species in the human oral cavity is well recognized, but a high proportion of them are presently uncultivable. Candidate division TM7 bacteria are almost always detected in metagenomic studies but have not yet been cultivated. In this paper, we identified candidate division TM7 bacterial phylotypes in mature plaque samples from around orthodontic bonds in subjects undergoing orthodontic treatment. Successive rounds of enrichment in laboratory media led to the isolation of a pure culture of one of these candidate division TM7 phylotypes. The bacteria formed filaments of 20 to 200 μm in length within agar plate colonies and in monospecies biofilms on salivary pellicle and exhibited some unusual morphological characteristics by transmission electron microscopy, including a trilaminated cell surface layer and dense cytoplasmic deposits. Proteomic analyses of cell wall protein extracts identified abundant polypeptides predicted from the TM7 partial genomic sequence. Pleiomorphic phenotypes were observed when the candidate division TM7 bacterium was grown in dual-species biofilms with representatives of six different oral bacterial genera. The TM7 bacterium formed long filaments in dual-species biofilm communities with Actinomyces oris or Fusobacterium nucleatum. However, the TM7 isolate grew as short rods or cocci in dual-species biofilms with Porphyromonas gingivalis, Prevotella intermedia, Parvimonas micra, or Streptococcus gordonii, forming notably robust biofilms with the latter two species. The ability to cultivate TM7 axenically should majorly advance understanding of the physiology, genetics, and virulence properties of this novel candidate division oral bacterium