Generation of a Maximally Entangled State Using Collective Optical Pumping.

We propose and implement a novel scheme for dissipatively pumping two qubits into a singlet Bell state. The method relies on a process of collective optical pumping to an excited level, to which all states apart from the singlet are coupled. We apply the method to deterministically entangle two trapped ^{40}Ca^{+} ions. Within 16 pumping cycles, an initially separable state is transformed into one with 83(1)% singlet fidelity, and states with initial fidelity of ⪆70% converge onto a fidelity of 93(1)%. We theoretically analyze the performance and error susceptibility of the scheme and find it to be insensitive to a large class of experimentally relevant noise sources.

Repeated multi-qubit readout and feedback with a mixed-species trapped-ion register.

Quantum error correction is essential for realizing the full potential of large-scale quantum information processing devices1,2. Fundamental to its experimental realization is the repetitive detection of errors via projective measurements of quantum correlations among qubits, as well as corrections using conditional feedback3. Repetitive application of such tasks requires that they neither induce unwanted crosstalk nor impede further control operations, which is challenging owing to the need to dissipatively couple qubits to the classical world for detection and reinitialization. For trapped ions, state readout involves scattering large numbers of resonant photons, which increases the probability of stray light causing errors on nearby qubits and leads to undesirable recoil heating of the ion motion. Here we demonstrate up to 50 sequential measurements of correlations between two beryllium ion microwave qubits using an ancillary optical qubit in a calcium ion, and implement feedback that allows us to stabilize two-qubit subspaces as well as Bell states, a class of maximally entangled states. Multi-qubit mixed-species gates are used to transfer information within the register from the qubit to the ancilla, enabling readout with negligible crosstalk to the data qubits. Heating of the ion motion during detection is mitigated by recooling all three ions using light that interacts with only the calcium ion, known as sympathetic cooling. A key element of our experimental setup is a powerful classical control system that features flexible in-sequence processing for feedback control. The methods employed here provide essential tools for scaling trapped-ion quantum computing, quantum-state control and entanglement-enhanced quantum metrology4.

Light-activated porphyrin-based formulations to inactivate bacterial spores.

AIM: The objective of this study was to develop porphyrin-based formulations to inactivate Bacillus spores. We probed the effect of porphyrins alone and in combination with germinants against both Bacillus cereus and Bacillus anthracis spores in the presence of light. METHODS AND RESULTS: We tested the effect of two different porphyrins, amine-modified protoporphyrin IX (PPIX) and meso-tetra (N-methyl-4-pyridyl) porphine tetra tosylate (TMP). Treatment with the porphyrins alone did not significantly influence spore viability. However, when spores were pretreated with a solution containing the germinants, l-alanine and inosine, the spore viability dropped by as much as 4.5 logs in the presence of light. The extent of inactivation depended on the germination conditions and the type of porphyrin used, with TMP being more effective. CONCLUSION: Porphyrins can be used effectively in combination with germinants to inactivate Bacillus spores. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study provide evidence that porphyrins can be used to inactivate Bacillus spores in the presence of germinants and light irradiation. This finding may be general and may be extended to spores of other pathogens.

Organization and delivery of long-term care in Singapore: present issues and future challenges.

This paper focuses on the Singaporean model of long-term care for older people. With only about 2% of the older population living in institutions, the mainstay of long-term care is community care. The reader is provided an overview of the Singaporean services, including case management, followed by a discussion of the current issues and future challenges. In keeping with the prospect of a rapidly aging population profile, the Singapore government plays a leading role in framing policy and planning for future needs of this sector of the population.

Prescription drug advertising trends: a study of oral hypoglycemics.

A content analysis of oral hypoglycemic drug advertisements was performed in selected medical journals published in the United States from 1963 to 1986. The 665 advertisements subsequently examined were studied for certain predetermined parameters in order to indicate trends. The trend results may be summarized as follows. As an extension of prescription drug advertising trends in general, oral hypoglycemic drug advertising showed an increasing length along with a subsequent decrease in the amount of space devoted to the copy portion of the advertisement. They also showed a decrease in the use of statistical information and rarely made references to competitors. Nongender specific, colored advertisements with product and use related appeals have become more common with the passage of time. Although the rationale and purpose behind advertising is unchanged, the format has changed considerably. These changes are primarily due to the enhancement of print technology and to some extent, the changing social environment.