High-fidelity initialization and control of electron and nuclear spins in a four-qubit register.

Single electron spins bound to multi-phosphorus nuclear spin registers in silicon have demonstrated fast (0.8 ns) two-qubit gates and long spin relaxation times (~30 s). In these spin registers, when the donors are ionized, the nuclear spins remain weakly coupled to their environment, allowing exceptionally long coherence times.

The Use of Exchange Coupled Atom Qubits as Atomic-Scale Magnetic Field Sensors.

Phosphorus atoms in silicon offer a rich quantum computing platform where both nuclear and electron spins can be used to store and process quantum information. While individual control of electron and nuclear spins has been demonstrated, the interplay between them during qubit operations has been largely unexplored. This study investigates the use of exchange-based operation between donor bound electron spins to probe the local magnetic fields experienced by the qubits with exquisite precision at the atomic scale.

Ramped measurement technique for robust high-fidelity spin qubit readout.

State preparation and measurement of single-electron spin qubits typically rely on spin-to-charge conversion where a spin-dependent charge transition of the electron is detected by a coupled charge sensor. For high-fidelity, fast readout, this process requires that the qubit energy is much larger than the temperature of the system limiting the temperature range for measurements. Here, we demonstrate an initialization and measurement technique that involves voltage ramps rather than static voltages allowing us to achieve state-to-charge readout fidelities above 99% for qubit energies almost half that required by traditional methods.

Coherent Control and Spectroscopy of a Semiconductor Quantum Dot Wigner Molecule.

Semiconductor quantum dots containing more than one electron have found wide application in qubits, where they enable readout and enhance polarizability. However, coherent control in such dots has typically been restricted to only the lowest two levels, and such control in the strongly interacting regime has not been realized. Here we report quantum control of eight different transitions in a silicon-based quantum dot.

Fabrication process and failure analysis for robust quantum dots in silicon.

We present an improved fabrication process for overlapping aluminum gate quantum dot devices on Si/SiGe heterostructures that incorporates low-temperature inter-gate oxidation, thermal annealing of gate oxide, on-chip electrostatic discharge (ESD) protection and an optimized interconnect process for thermal budget considerations. This process reduces gate-to-gate leakage, damage from ESD, dewetting of aluminum and formation of undesired alloys in device interconnects. Additionally, cross-sectional scanning transmission electron microscopy (STEM) images elucidate gate electrode morphology in the active region as device geometry is varied.

Exploiting a Single-Crystal Environment to Minimize the Charge Noise on Qubits in Silicon.

Electron spins in silicon offer a competitive, scalable quantum-computing platform with excellent single-qubit properties. However, the two-qubit gate fidelities achieved so far have fallen short of the 99% threshold required for large-scale error-corrected quantum computing architectures. In the past few years, there has been a growing realization that the critical obstacle in meeting this threshold in semiconductor qubits is charge noise arising from the qubit environment.

Abdominal pain is a common and recurring problem in paediatric emergency departments.

Aim: Abdominal pain is a frequent reason for paediatric emergency department visits, but specific research is lacking. Our aim was to obtain information on the diagnosis of abdominal pain and what healthcare services children with this condition need.

Methods: This retrospective study focused on patients visiting the emergency department of the Children's Hospital Iceland in 2010 with abdominal pain and any subsequent visits up to 1 January 2015.

Why chlorate occurs in potable water and processed foods: a critical assessment and challenges faced by the food industry.

Recently, reports have been published on the occurrence of chlorate mainly in fruits and vegetables. Chlorate is a by-product of chlorinating agents used to disinfect water, and can be expected to be found in varying concentrations in drinking water. Data on potable water taken at 39 sampling points across Europe showed chlorate to range from < 0.

Characterization of a gate-defined double quantum dot in a Si/SiGe nanomembrane.

We report the fabrication and characterization of a gate-defined double quantum dot formed in a Si/SiGe nanomembrane. In the past, all gate-defined quantum dots in Si/SiGe heterostructures were formed on top of strain-graded virtual substrates. The strain grading process necessarily introduces misfit dislocations into a heterostructure, and these defects introduce lateral strain inhomogeneities, mosaic tilt, and threading dislocations.

1- and 2-year-olds' expectations about third-party communicative actions.

Infants expect people to direct actions toward objects, and they respond to actions directed to themselves, but do they have expectations about actions directed to third parties? In two experiments, we used eye tracking to investigate 1- and 2-year-olds' expectations about communicative actions addressed to a third party. Experiment 1 presented infants with videos where an adult (the Emitter) either uttered a sentence or produced non-speech sounds. The Emitter was either face-to-face with another adult (the Recipient) or the two were back-to-back.

Infants' expectations about gestures and actions in third-party interactions.

We investigated 14-month-old infants' expectations toward a third party addressee of communicative gestures and an instrumental action. Infants' eye movements were tracked as they observed a person (the Gesturer) point, direct a palm-up request gesture, or reach toward an object, and another person (the Addressee) respond by grasping it. Infants' looking patterns indicate that when the Gesturer pointed or used the palm-up request, infants anticipated that the Addressee would give the object to the Gesturer, suggesting that they ascribed a motive of request to the gestures.

Mitochondrial encephalomyopathy with elevated methylmalonic acid is caused by SUCLA2 mutations.

We have identified 12 patients with autosomal recessive mitochondrial encephalomyopathy with elevated methylmalonic acid. The disorder has a high incidence of 1 in 1700 in the Faroe Islands due to a founder effect, and a carrier frequency of 1 in 33. The symptoms comprise hypotonia, muscle atrophy, hyperkinesia, severe hearing impairment and postnatal growth retardation.

Paediatric burns in Iceland. Hospital admissions 1982-1995, a populations based study.

Epidemiological data of 290 children admitted to the Paediatric Department, University Hospital of Iceland, over a 14 year period, 1982-1995, are presented. The sex ratio boys/girls was 1.6.

[The epidemiology of serious burn injuries in Iceland 1988-1992.].

Introduction: Due to widespread access to hot water in Iceland it has been suspected that the incidence of burn injury is higher compared to other countries. The epidemiology of severe burn injury needing hospitalization was studied.

Material And Methods: The files of all patients who were diagnosed with burn injury and admitted to the four largest community hospitals in Iceland were retrospectively reviewed.

[Burn injuries in children in Iceland between 1982-1995.].

Objective: To increase our knowledge of burn injuries in children in Iceland and to induce education and prevention in order to reduce the incidence of burn injuries among children.

Material And Methods: Data was collected from hospital records of all children 15 years and younger admitted with burn injuries to the University Hospital of Iceland, Paediatric Department, from 1982-1995.

Results: There were 290 children admitted, 179 boys and 111 girls, sex ratio 1.

[The ΔF508 mutation in cystic fibrosis patients].

Cystic fibrosis is a serious autosomal recessive disorder. It is commonest among the white Caucasian populations in North and Western Europe. However, no information is available on this disease in Iceland.