Generating Greenberger-Horne-Zeilinger states with squeezing and postselection.

Many quantum state preparation methods rely on a combination of dissipative quantum state initialization followed by unitary evolution to a desired target state. Here we demonstrate the usefulness of quantum measurement as an additional tool for quantum state preparation. Starting from a pure separable multipartite state, a control sequence, which includes rotation, spin squeezing via one-axis twisting, quantum measurement, and postselection, generates highly entangled multipartite states, which we refer to as (PS) states.

Improving aesthetic outcomes after head and neck reconstruction.

Purpose Of Review: Tremendous advancements have been made in head and neck reconstruction following oncologic resection. Despite this, many patients are left with disfiguring postoperative changes. The focus of this review highlights various techniques aimed at improving aesthetic outcomes following head and neck cancer therapy, with a focus on liposuction and fat augmentation.

Analytically exploiting noise correlations inside the feedback loop to improve locked-oscillator performance.

We introduce concepts from optimal estimation to the stabilization of precision frequency standards limited by noisy local oscillators. We develop a theoretical framework casting various measures for frequency standard variance in terms of frequency-domain transfer functions, capturing the effects of feedback stabilization via a time series of Ramsey measurements. Using this framework, we introduce an optimized hybrid predictive feedforward measurement protocol that employs results from multiple past measurements and transfer-function-based calculations of measurement covariance to improve the accuracy of corrections within the feedback loop.

Coupled optical resonance laser locking.

We have demonstrated simultaneous laser frequency stabilization of a UV and IR laser, to coupled transitions of ions in the same spectroscopic sample, by detecting only the absorption of the UV laser. Separate signals for locking the different lasers are obtained by modulating each laser at a different frequency and using lock-in detection of a single photodiode signal. Experimentally, we simultaneously lock a 369 nm and a 935 nm laser to the (2)S(1/2) → (2)(P(1/2) and (2)D(3/2) → (3)D([3/2]1/2) transitions, respectively, of Yb(+) ions generated in a hollow cathode discharge lamp.

Prevalence and clinical presentation of HIV positive female psychiatric inpatients.

Objective: Literature on the prevalence and clinical presentation of South African psychiatric HIV positive patients as well as their management is lacking. This study was performed to investigate these parameters.

Method: A prospective study to investigate the prevalence and clinical presentation of HIV positive psychiatric female patients admitted to an acute ward (female psychiatric ward Cecilia Makiwane Hospital, East London Hospital Complex) was undertaken for a one year period from June 2009 to May 2010.

High-order noise filtering in nontrivial quantum logic gates.

Treating the effects of a time-dependent classical dephasing environment during quantum logic operations poses a theoretical challenge, as the application of noncommuting control operations gives rise to both dephasing and depolarization errors that must be accounted for in order to understand total average error rates. We develop a treatment based on effective Hamiltonian theory that allows us to efficiently model the effect of classical noise on nontrivial single-bit quantum logic operations composed of arbitrary control sequences. We present a general method to calculate the ensemble-averaged entanglement fidelity to arbitrary order in terms of noise filter functions, and provide explicit expressions to fourth order in the noise strength.

Spectroscopy and thermometry of drumhead modes in a mesoscopic trapped-ion crystal using entanglement.

We demonstrate spectroscopy and thermometry of individual motional modes in a mesoscopic 2D ion array using entanglement-induced decoherence as a method of transduction. Our system is a ~400 μm-diameter planar crystal of several hundred 9Be(+) ions exhibiting complex drumhead modes in the confining potential of a Penning trap. Exploiting precise control over the 9Be(+) valence electron spins, we apply a homogeneous spin-dependent optical dipole force to excite arbitrary transverse modes with an effective wavelength approaching the interparticle spacing (~20 μm).

Engineered two-dimensional Ising interactions in a trapped-ion quantum simulator with hundreds of spins.

The presence of long-range quantum spin correlations underlies a variety of physical phenomena in condensed-matter systems, potentially including high-temperature superconductivity. However, many properties of exotic, strongly correlated spin systems, such as spin liquids, have proved difficult to study, in part because calculations involving N-body entanglement become intractable for as few as N ≈ 30 particles. Feynman predicted that a quantum simulator--a special-purpose 'analogue' processor built using quantum bits (qubits)--would be inherently suited to solving such problems.

Laser induced and controlled chemical reaction of carbon monoxide and hydrogen.

Bimolecular chemical reaction control of gaseous CO and H(2) at room temperature and atmospheric pressure, without any catalyst, using shaped femtosecond laser pulses is presented. High intensity laser radiation applied to a reaction cell facilitates non-resonant bond breakage and the formation of a range of ions, which can then react to form new products. Stable reaction products are measured after irradiation of a reaction cell, using time of flight mass spectroscopy.

Phase-coherent detection of an optical dipole force by Doppler velocimetry.

We report phase-coherent Doppler detection of optical dipole forces using large ion crystals in a Penning trap. The technique is based on laser Doppler velocimetry using a cycling transition in 9Be+ near 313 nm and the center-of-mass (COM) ion motional mode. The optical dipole force is tuned to excite the COM mode, and measurements of photon arrival times synchronized with the excitation potential show oscillations with a period commensurate with the COM motional frequency.

Precessive sand ripples in intense steady shear flows.

We describe experimental observations of fully developed, large-amplitude bars under the action of a shearing fluid. The experiments were performed in an annular tank filled with water and sheared above by a steady motor source. The same steady shearing flow can produce a variety of different erodible bed manifestations: advective or precessive bars, which refer to bar structures with global regularity and a near-steady precession velocity; interactive bars, the structure of which depends on local rearrangements, which are in turn a response to complex background topography; and dispersive bars, which are created when an initially isolated mound of sand evolves into a train of sand ripples.

Decoherence due to elastic Rayleigh scattering.

We present theoretical and experimental studies of the decoherence of hyperfine ground-state superpositions due to elastic Rayleigh scattering of light off resonant with higher lying excited states. We demonstrate that under appropriate conditions, elastic Rayleigh scattering can be the dominant source of decoherence, contrary to previous discussions in the literature. We show that the elastic-scattering decoherence rate of a two-level system is given by the square of the difference between the elastic-scattering amplitudes for the two levels, and that for certain detunings of the light, the amplitudes can interfere constructively even when the elastic-scattering rates from the two levels are equal.

Ultrasensitive detection of force and displacement using trapped ions.

The ability to detect extremely small forces and nanoscale displacements is vital for disciplines such as precision spin-resonance imaging, microscopy, and tests of fundamental physical phenomena. Current force-detection sensitivity limits have surpassed 1 aN Hz(-1/2) (refs 6,7) through coupling of nanomechanical resonators to a variety of physical readout systems. Here, we demonstrate that crystals of trapped atomic ions behave as nanoscale mechanical oscillators and may form the core of exquisitely sensitive force and displacement detectors.

Optimized noise filtration through dynamical decoupling.

Recent studies have shown that applying a sequence of Hahn spin-echo pulses to a qubit system at judiciously chosen intervals can, in certain noise environments, greatly improve the suppression of phase errors compared to traditional dynamical decoupling approaches. By enforcing a simple analytical condition, we obtain sets of dynamical decoupling sequences that are designed for optimized noise filtration, but are independent of the noise spectrum up to a single scaling factor set by the coherence time of the system. These sequences are tested in a model qubit system, ;{9}Be;{+} ions in a Penning trap.

Optimized dynamical decoupling in a model quantum memory.

Any quantum system, such as those used in quantum information or magnetic resonance, is subject to random phase errors that can dramatically affect the fidelity of a desired quantum operation or measurement. In the context of quantum information, quantum error correction techniques have been developed to correct these errors, but resource requirements are extraordinary. The realization of a physically tractable quantum information system will therefore be facilitated if qubit (quantum bit) error rates are far below the so-called fault-tolerance error threshold, predicted to be of the order of 10(-3)-10(-6).

Matter-wave decoherence due to a gas environment in an atom interferometer.

Decoherence due to scattering from background gas particles is observed for the first time in a Mach-Zehnder atom interferometer, and compared with decoherence due to scattering photons. A single theory is shown to describe decoherence due to scattering either atoms or photons. Predictions from this theory are tested by experiments with different species of background gas, and also by experiments with different collimation restrictions on an atom beam interferometer.

'Double' teeth-a diagnostic conundrum.

A 'double' tooth is an uncommon dental developmental anomaly that can occur in the deciduous and/or permanent dentition. It is not always possible to differentiate clinically between fusion and gemination. Clinical and radiographic examination, as well as a histological assessment, can help to differentiate between fusion and gemination.

Organ donation and transplantation within the Zulu culture.

Greater knowledge and technological advancement in the field of transplantation has increased the demand for organ donation beyond the supply of organs, especially among the black communities. This imbalance arises from the few sources of organs, limitations on the techniques of organ retrieval, disparities in the allocation of organs and socio-cultural factors. The aim of this study was to investigate the extent to which Zulu cultural norms and social structures influence an individual's decision to donate an organ or to undergo transplantation.

Clinical association of acute lateral ankle sprain with syndesmotic involvement: a stress radiography and magnetic resonance imaging study.

Background: Information concerning the clinical association between syndesmosis injury and grade of lateral ankle ligament damage would aid in the diagnosis and treatment of ankle sprains.

Hypothesis: Evaluation of lateral ligament injury in terms of percentage tear of both the anterior talofibular and calcaneofibular ligaments can provide information on the extent of syndesmotic involvement.

Study Design: Prospective cohort study.

Organ donation: attitude and knowledge of nurses in South Africa.

Various factors influence the process of organ donation. As a result, there is a shortage of organs for transplant. Poor communication and cooperation between transplant coordinators and intensive care nursing staff can lead to the non-referral of potential organ donors, which is detrimental to the process.

Leadership development in a nursing service. A South African ethnographic perspective.

Leadership development at operational level in a nursing service is important to cope with all the transformation required. The purpose with this study is to explore and describe the views of black professional nurses on leadership behaviour, within the context of an operating theatre department, and to determine the influence of their occupational history on these views. An exploratory and descriptive research design, with an ethnographic perspective, was employed by means of semi-structured interviews (views on leadership) and questionnaires (occupational history).

Malaria. A challenge for the haemodialysis and intensive care nurse.

Malaria is the world's most important tropical parasitic disease. In many developing countries, and Africa in particular, malaria exacts an enormous toll in lives, medical costs, and days of lost labour. Through the use of case studies, this paper explores the effects of malaria and the patient management by the haemodialysis and intensive care nurse.

[Nurses' and patients' experience of combined health service delivery to all population groups in a hospital].

In a community hospital in Gauteng, the hospital management had, on short notice, to provide combined health services to all population groups. In the past different health services were delivered to each population group. The integration of health service delivery was a sudden change.

[The effect of preoperative teaching on the emotional attitude of patients undergoing coronary bypass surgery].

It appears that the emotions of patients in the process of undergoing coronary artery bypass graft surgery have an influence on the rate of mortality. The purpose of this study is to determine if the life-style functioning of the patients can be improved by means of a pre-operative rehabilitative educational programme introduced by the professional nurse. A conceptual framework of reference was compiled after completion of the literature review.

[Support systems for patients with coronary bypass].

The rehabilitation of the coronary artery bypass patient should be a continuation of the contact which exists during the hospitalisation phase, with specific reference to the pre-discharge phase. As a member of the health team, the nurse makes the most input during this phase because she is the one who is in constant contact with the patient and his family. The purpose of this study is to determine, by means of set criteria and within a nursing perspective, the contributions that are made by various support groups to the rehabilitation of persons who have undergone coronary artery bypass surgery.