Benchmarking an 11-qubit quantum computer.

The field of quantum computing has grown from concept to demonstration devices over the past 20 years. Universal quantum computing offers efficiency in approaching problems of scientific and commercial interest, such as factoring large numbers, searching databases, simulating intractable models from quantum physics, and optimizing complex cost functions. Here, we present an 11-qubit fully-connected, programmable quantum computer in a trapped ion system composed of 13 171Yb+ ions. We demonstrate average single-qubit gate fidelities of 99.5[Formula: see text], average two-qubit-gate fidelities of 97.5[Formula: see text], and SPAM errors of 0.7[Formula: see text]. To illustrate the capabilities of this universal platform and provide a basis for comparison with similarly-sized devices, we compile the Bernstein-Vazirani and Hidden Shift algorithms into our native gates and execute them on the hardware with average success rates of 78[Formula: see text] and 35[Formula: see text], respectively. These algorithms serve as excellent benchmarks for any type of quantum hardware, and show that our system outperforms all other currently available hardware.

Outcomes in children treated for tuberculosis with the new dispersible fixed-dose combinations in Port Moresby.

SETTING: The new child-friendly fixed dose combinations (FDCs) were introduced at Port Moresby General Hospital, Papua New Guinea, in 2016 for the first-line treatment of children (aged <15 years) with tuberculosis (TB) who weighed <25 kg. OBJECTIVE: To describe the characteristics and outcomes for children treated with the new FDCs, and to identify risk factors for unfavourable treatment outcomes. DESIGN: This was a retrospective cohort study of all children treated for TB with the FDCs from August 2016 to August 2017. RESULTS: Of 713 children included, 488 (68%) were diagnosed with pulmonary TB. Only 6 (0.8%) TB cases were bacteriologically confirmed and human immunodeficiency virus (HIV) status was known in 50%. Treatment outcomes were favourable in 425 (60%) children. Of 288 children with unfavourable outcomes, there were 242 (84%) with loss to follow-up (LTFU) and 25 (8.4%) were known to have died. Children who were severely underweight (weight-for-age Z score <-3) on presentation were at greater risk of LTFU compared to children of normal weight on multivariable analysis (aRR 1.3, 95%CI 1.0-1.6, P < 0.05). CONCLUSION: Alternative models of care to decrease LTFU during treatment are needed, including integration with nutritional support. Improving diagnosis through microbiological confirmation of TB and HIV are major challenges to be addressed.

Arbitrary waveform generator for quantum information processing with trapped ions.

Atomic ions confined in multi-electrode traps have been proposed as a basis for scalable quantum information processing. This scheme involves transporting ions between spatially distinct locations by use of time-varying electric potentials combined with laser or microwave pulses for quantum logic in specific locations. We report the development of a fast multi-channel arbitrary waveform generator for applying the time-varying electric potentials used for transport and for shaping quantum logic pulses. The generator is based on a field-programmable gate array controlled ensemble of 16-bit digital-to-analog converters with an update frequency of 50 MHz and an output range of ±10 V. The update rate of the waveform generator is much faster than relevant motional frequencies of the confined ions in our experiments, allowing diabatic control of the ion motion. Numerous pre-loaded sets of time-varying voltages can be selected with 40 ns latency conditioned on real-time signals. Here we describe the device and demonstrate some of its uses in ion-based quantum information experiments, including speed-up of ion transport and the shaping of laser and microwave pulses.

Microwave quantum logic gates for trapped ions.

Control over physical systems at the quantum level is important in fields as diverse as metrology, information processing, simulation and chemistry. For trapped atomic ions, the quantized motional and internal degrees of freedom can be coherently manipulated with laser light. Similar control is difficult to achieve with radio-frequency or microwave radiation: the essential coupling between internal degrees of freedom and motion requires significant field changes over the extent of the atoms' motion, but such changes are negligible at these frequencies for freely propagating fields. An exception is in the near field of microwave currents in structures smaller than the free-space wavelength, where stronger gradients can be generated. Here we first manipulate coherently (on timescales of 20 nanoseconds) the internal quantum states of ions held in a microfabricated trap. The controlling magnetic fields are generated by microwave currents in electrodes that are integrated into the trap structure. We also generate entanglement between the internal degrees of freedom of two atoms with a gate operation suitable for general quantum computation; the entangled state has a fidelity of 0.76(3), where the uncertainty denotes standard error of the mean. Our approach, which involves integrating the quantum control mechanism into the trapping device in a scalable manner, could be applied to quantum information processing, simulation and spectroscopy.

Efficient fiber optic detection of trapped ion fluorescence.

Integration of fiber optics may play a critical role in the development of quantum information processors based on trapped ions and atoms by enabling scalable collection and delivery of light and coupling trapped ions to optical microcavities. We trap 24Mg+ ions in a surface-electrode Paul trap that includes an integrated optical fiber for detecting 280-nm fluorescence photons. The collection numerical aperture is 0.37, and total collection efficiency is 2.1%. The ion can be positioned between 80 and 100 µm from the tip of the fiber by use of an adjustable rf pseudopotential.

Entangled mechanical oscillators.

Hallmarks of quantum mechanics include superposition and entanglement. In the context of large complex systems, these features should lead to situations as envisaged in the 'Schrödinger's cat' thought experiment (where the cat exists in a superposition of alive and dead states entangled with a radioactive nucleus). Such situations are not observed in nature. This may be simply due to our inability to sufficiently isolate the system of interest from the surrounding environment-a technical limitation. Another possibility is some as-yet-undiscovered mechanism that prevents the formation of macroscopic entangled states. Such a limitation might depend on the number of elementary constituents in the system or on the types of degrees of freedom that are entangled. Tests of the latter possibility have been made with photons, atoms and condensed matter devices. One system ubiquitous to nature where entanglement has not been previously demonstrated consists of distinct mechanical oscillators. Here we demonstrate deterministic entanglement of separated mechanical oscillators, consisting of the vibrational states of two pairs of atomic ions held in different locations. We also demonstrate entanglement of the internal states of an atomic ion with a distant mechanical oscillator. These results show quantum entanglement in a degree of freedom that pervades the classical world. Such experiments may lead to the generation of entangled states of larger-scale mechanical oscillators, and offer possibilities for testing non-locality with mesoscopic systems. In addition, the control developed here is an important ingredient for scaling-up quantum information processing with trapped atomic ions.

High-fidelity transport of trapped-ion qubits through an X-junction trap array.

We report reliable transport of (9)Be(+) ions through an "X junction" in a 2D trap array that includes a separate loading and reservoir zone. During transport the ion's kinetic energy in its local well increases by only a few motional quanta and internal-state coherences are preserved. We also examine two sources of energy gain during transport: a particular radio-frequency noise heating mechanism and digital sampling noise. Such studies are important to achieve scaling in a trapped-ion quantum information processor.

Trapped-ion quantum logic gates based on oscillating magnetic fields.

Oscillating magnetic fields and field gradients can be used to implement single-qubit rotations and entangling multiqubit quantum gates for trapped-ion quantum information processing (QIP). With fields generated by currents in microfabricated surface-electrode traps, it should be possible to achieve gate speeds that are comparable to those of optically induced gates for realistic distances between the ion crystal and the electrode surface. Magnetic-field-mediated gates have the potential to significantly reduce the overhead in laser-beam control and motional-state initialization compared to current QIP experiments with trapped ions and will eliminate spontaneous scattering, a fundamental source of decoherence in laser-mediated gates.

Anthropometrical antecedents of non-insulin dependent diabetes mellitus: an age and sex matched comparison study of anthropometric indices in schoolchildren from a high prevalence Port Moresby community.

Anthropometrical indices of 66 school children aged between 7 and 9 years from a community with a very high prevalence of non-insulin dependent diabetes mellitus (NIDDM) were compared with those of age and sex matched school children from two low prevalence communities. Two way analysis of variance indicated that case children of both sexes were significantly lighter (P < 0.001), shorter (P < 0.001) and had lower body mass indices (BMI) (P < 0.001) than their comparisons but had greater triceps skinfold thickness (TSFT) (P = 0.01). These differences may be a reflection of subtle changes in metabolism in children destined, without intervention, to develop NIDDM. Anthropometrical indices may therefore have a role to play in the prediction of future disease. Although not the prime objective of the study, an analysis of available birth weights indicated a lower mean birth weight for the cases than the controls (difference of means, 0.35 kg; 95% confidence intervals (CI95%). 0.13-0.57). This finding is consistent with the theory that impaired intrauterine growth may predispose to NIDDM.

Flow analysis of red blood cell through microvascular bifurcations.

The motion of a rigid particle suspended in two-dimensional flow through bifurcations of diverging microvessels (DMs), and converging microvessels (CMs) is dependent on multiple complex factors that include the geometry of the network, the angle of the bifurcation, the pressure gradient across the microvessel, the geometry of the cells and their radial location in the vessels. To determine how these parameters affect cell trajectories and flux into downstream branches of CMs and DMs, the motion of cells flowing into a DMs and CMs bifurcation, with a 45 degrees branch angle has been modelled, for every location by means of the finite-difference analysis (FDA). The modeling data was compared with direct experimental data from converging and diverging microvessels obtained from mesenteric microcirculation of the rat. Detailed statistical analysis showed significant correlation between the modeling data and experimental data. This model provides estimates of RBC flow along the trajectory path through bifurcations of CMs and DMs; sites which may be crucial for flow stoppage, depending on the vessel diameter and cell deformability.

[Perforation of the nasal septum caused by leishmaniasis]. / Perforation de la cloison nasale par leishmaniose

The perforation of the nasal septum with the crusted ulcer surrounding accompanied by the erythema of skin of the vestibule should suggest the possibility of leishmaniosis. The microscopic examination and culture of the secretions in N.N.N. culture medium provides confirmation of the diagnosis and the specific treatment could then be instituted.