1,659 research outputs found

    Generation of spin-motion entanglement in a trapped ion using long-wavelength radiation

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    Applying a magnetic-field gradient to a trapped ion allows long-wavelength radiation to produce a mechanical force on the ion's motion when internal transitions are driven. We demonstrate such a coupling using a single trapped Yb+171 ion and use it to produce entanglement between the spin and motional state, an essential step toward using such a field gradient to implement multiqubit operations

    Experimental investigations of bolted segmental grey cast iron lining behaviour

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    The need for the research reported in this paper was driven by the Crossrail project in London for which new tunnels were constructed close to numerous existing operational tunnels of the London Underground (LU) network. This research is based on experimental work conducted on half-scale grey cast iron (GCI) tunnel lining segments with chemical composition similar to the Victorian age GCI segments in the LU network. This paper discusses the deformation behaviour of the bolted segmental lining under the influence of factors such as overburden pressure, bolt preload and presence of grommets at small distortions. The measured behaviour of the segmental lining is compared against the calculated response of a continuous lining based on the assumption of elasticity. The industry practice for tunnel lining assessment is to calculate the induced bending moment in the tunnel lining using an elastic continuum model, while adopting a reduced lining stiffness to take into account the presence of the joints. Case studies have recorded that both loosening and tightening of lining bolts have been used as mitigation measures to reduce the impact of new tunnel excavations on existing GCI tunnels. The experimental work on the half-scale GCI lining has shown that a bolted segmental lining behaves as a continuous ring under small distortions imposed when subjected to hoop forces relevant to the depth of burial of LU tunnels. In the presence of hoop force, joint opening was minimal and the magnitude of preload in the bolts had little impact on the behaviour of the lining. It is therefore concluded that disturbance of the bolts in existing tunnels is not recommended as a mitigation measure as in addition to being ineffective it is both time consuming and introduces the risk of damaging the tunnel lining flanges

    Ground-state cooling of a trapped ion Using long-wavelength radiation

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    We demonstrate ground-state cooling of a trapped ion using radio-frequency (rf) radiation. This is a powerful tool for the implementation of quantum operations, where rf or microwave radiation instead of lasers is used for motional quantum state engineering. We measure a mean phonon number of nÂŻ=0.13(4) after sideband cooling, corresponding to a ground-state occupation probability of 88(7)%. After preparing in the vibrational ground state, we demonstrate motional state engineering by driving Rabi oscillations between the |n=0⟩ and |n=1⟩ Fock states. We also use the ability to ground-state cool to accurately measure the motional heating rate and report a reduction by almost 2 orders of magnitude compared with our previously measured result, which we attribute to carefully eliminating sources of electrical noise in the system

    Efficient preparation and detection of microwave dressed-state qubits and qutrits with trapped ions

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    We demonstrate a method for preparing and detecting all eigenstates of a three-level microwave dressed system with a single trapped ion. The method significantly reduces the experimental complexity of gate operations with dressed-state qubits, as well as allowing all three of the dressed states to be prepared and detected, thereby providing access to a qutrit that is well protected from magnetic field noise. In addition, we demonstrate individual addressing of the clock transitions in two ions using a strong static magnetic field gradient, showing that our method can be used to prepare and detect microwave dressed states in a string of ions when performing multi-ion quantum operations with microwave and radio frequency fields. The individual addressability of clock transitions could also allow for the control of pairwise interaction strengths between arbitrary ions in a string using lasers

    Creep behaviour of structured clays in triaxial stress space: theory and experimental investigation

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    This paper investigates the time-dependent behaviour of structured clays in triaxial stress space both theoretically and experimentally. A range of existing theoretical frameworks and phenomenological equations are reviewed and discussed in their ability to interpret the creep behaviour at different states in q:pâ€Č stress space. New experimental results are presented for two structured clays subjected to complex loading conditions. Each test consists of a defined stress path with intermediate stages of creep. Considerable creep deformations were observed at all anisotropic effective stress conditions. Measured viscous deformations were observed to be related to the stress state, approaching stress path and degree of structure present in the soil. The incremental strain ratio, ΔΔs/ΔΔvol , measured during constant stress was found to rotate counter-clockwise as a result of drained shearing towards failure for all tests. The experiments also show that for very small stress increments, phenomenological and empirical relations incorrectly predict the development of creep strains with time

    The narratives of Hardship: : The new and the old poor in the aftermath of the 2008 crisis in Europe

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    This document is the Accepted Manuscript version of the following article: Hulya Dagdeviren, Matthew Donoghue, and Lars Meier, ‘The narratives of hardship: the new and the old poor in the aftermath of the 2008 crisis in Europe’, The Sociological Review, vol. 65 (2): 369-385, May 2017. The final, definitive version of record is available online at doi: https://doi.org/10.1111/1467-954X.12403. Published by SAGE.This paper examines poverty and hardship in Europe after the 2008 crisis, using household interviews in nine European countries. A number of findings deserve highlighting. First, making a distinction between ‘the old poor’ (those who lived in poverty before as well as after the crisis) and ‘the new poor’ (thosewho fell into hardship after the crisis), we show that hardship is experienced quite differently by these groups. Second, the household narratives showed that while material deprivations constitute an important aspect of hardship, the themes of insecurity and dependency also emerged as fundamental dimensions. In contrast to popular political discourse in countries such as the UK, dependency on welfare or family was experienced as a source of distress and manifested as a form of hardship by participants in all countries covered in this study.Peer reviewedFinal Accepted Versio

    Plant closures, precariousness and policy responses:revisiting MG Rover 10 years on

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    With automotive plants being closed in Australia and western Europe, this article reflects on the employment status of ex-MG Rover (MGR) workers following the closure of the Longbridge plant in 2005. In particular, it draws on Standing's typology of labour market insecurity and uses a mixed-methods approach including an analysis of a longitudinal survey of some 200 ex-MGR workers, and in-depth interviews with ex-workers and policy-makers. While the policy response to the closure saw significant successes in terms of the great majority of workers successfully adjusting into re-employment, and with positive findings in terms of re-training and education, the paper finds significant challenges in terms of security of employment, income, job quality and representation at work years after closure. In particular, the paper posits that the general lack of attention to employment security at the macrolevel effectively undermined elements of a positive policy response over the longer run. This in turn suggests longer-term policy measures are required to address aspects of precariousness at work

    ÂżQue permite el autocontrol? Un test de glucosa, fructosa y activaciĂłn del nervio vago como posibles factores

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    This study replicated the study by Miller, Bourrasseau, and Blampain (2013) on the effects of fructose and glucose on self-control. It also investigated these authors' suggestion that self-control may be under the influence of the vagus nerve, which can be activated by forceful exhalation in the Valsalva manoeuvre. The participants (N = 101) were assigned to one of five conditions: three groups that received a solution of either glucose, fructose, or a placebo sweetener (solution condition); and two groups that underwent the Valsalva manoeuvre (VM and VM-control). Participants in the solution condition groups ingested one of the three sweeteners, whereas those in the VM and VM-control conditions were required to blow or not blow into a manometer for 15 seconds, respectively. The number of anagrams that participants subsequently completed was used to assess their level of self-control. In contrast to the results obtained by Miller et al. (2013), it was found that fructose, glucose, and VM did not increase the participants' levels of self-control compared to control subjects. These negative results concur with several recent studies which document the difficulty of replicating published findings in psychology.Este estudio es una rĂ©plica del estudio realizado por Miller, Bourrasseau y Blampain (2013) sobre los efectos de la fructosa y la glucosa en el autocontrol. TambiĂ©n se contrastĂł la sugerencia de estos autores de que el autocontrol puede estar bajo la influencia del nervio vago, que puede ser activado mediante una exhalaciĂłn enĂ©rgica mediante la manio-bra de Valsalva. Los participantes (N=101) fueron asignados a una de las cinco condiciones: tres grupos que recibieron una soluciĂłn (glucosa, fructosa o un edulcorante placebo) y dos condiciones que ejecutaban la maniobra de Valsalva (MV, y MV-control). Los participantes de la condiciĂłn de “soluciĂłn” ingirieron uno de los tres edulcorantes, mientras que los participantes de la condiciĂłn MV y MV-control, se les pidiĂł que soplasen/no soplasen dentro de un manĂłmetro durante 15 segundos, respectivamente. El nĂșmero de anagramas que los participantes completaron posteriormente se utilizĂł para evaluar su nivel de autocontrol. Contrariamente a los resultados de Miller et al. (2013), ni la fructosa ni la glucosa aumentaron los niveles de autocontrol de los participantes en comparaciĂłn con los sujetos control, ni MV afectĂł al autocontrol. Estos resultados negativos coinciden con varios estudios recientes que documentan la dificultad de replicar los hallazgos publicados en la psicologĂ­a
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