Twin polaritons in semiconductor microcavities

The quantum correlations between the beams generated by polariton pair scattering in a semiconductor microcavity above the parametric oscillation threshold are computed analytically. The influence of various parameters like the cavity-exciton detuning, the intensity mismatch between the signal and idler beams and the amount of spurious noise is analyzed. We show that very strong quantum correlations between the signal and idler polaritons can be achieved. The quantum effects on the outgoing light fields are strongly reduced due to the large mismatch in the coupling of the signal and idler polaritons to the external photons

How much money can be saved by applying intravenous antibiotics once instead of several times a day?

Background: The preparation, administration and monitoring of intravenous (IV) applications are time consuming and require human resources. We estimated the potential time and cost savings by replacing antibiotics given 3-4 times daily with antibiotics with similar spectrum and efficacy given once daily. Methods: The savings of indirect costs were estimated based on the antibiotic consumption data of a two-year period (i.e. 2007 and 2008), a nurse's mean workload per application and the average nurse's salary in Switzerland. Results: The consumption of IV antibiotics in 2007 and 2008 at the University Hospital of Basel was 29.0 and 32.2 defined daily doses (DDD) per 100 patient days, respectively. Nurses spent an estimated 13,786h on the application of the estimated 82,715 does of IV antibiotics. A total of 56,404 applications or nursing staff time costs of 338,436 Swiss Francs (CHF; 236,669 €), equal to 16% of the overall costs spent on purchasing antibiotics in the year 2008, may have been saved by switching multiple-dose antibiotics to a hypothetical once-daily antibiotic. Including disposable materials, 21% or 456,884 CHF (319,499 €) could be saved annually (purchase costs not taken into account). Conclusion: We found a potential cost saving of 21% of the purchase costs in a 750-bed institution. Hence, indirect costs should be included in the calculation of the total cost for the application of broad-spectrum IV antibiotics. Switching from a 3-4 times daily application to a once-daily antibiotic should be considered if a once-daily antibiotic is deemed equally effective and has a similar spectru

Quantum interference of ultrastable twin optical beams

We report the first measurement of the quantum phase-difference noise of an ultrastable nondegenerate optical parametric oscillator that emits twin beams classically phase-locked at exact frequency degeneracy. The measurement illustrates the property of a lossless balanced beam-splitter to convert number-difference squeezing into phase-difference squeezing and, thus, provides indirect evidence for Heisenberg-limited interferometry using twin beams. This experiment is a generalization of the Hong-Ou-Mandel interference effect for continuous variables and constitutes a milestone towards continuous-variable entanglement of bright, ultrastable nondegenerate beams.Comment: 4 pages, 4 figs, accepted by Phys. Rev. Let

Conditional preparation of a quantum state in the continuous variable regime: generation of a sub-Poissonian state from twin beams

We report the first experimental demonstration of conditional preparation of a non classical state of light in the continuous variable regime. Starting from a non degenerate OPO which generates above threshold quantum intensity correlated signal and idler "twin beams", we keep the recorded values of the signal intensity only when the idler falls inside a band of values narrower than its standard deviation. By this very simple technique, we generate a sub-Poissonian state 4.4dB below shot noise from twin beams exhibiting 7.5dB of noise reduction in the intensity difference.Comment: 4 pages, Accepted in Phys. Rev. Let

Polyol synthesis, functionalisation, and biocompatibility studies of superparamagnetic iron oxide nanoparticles as potential MRI contrast agents

Iron oxide nanoparticles (IONPs) of low polydispersity were obtained through a simple polyol synthesis in high pressure and high temperature conditions. The control of the size and morphology of the nanoparticles was studied by varying the solvent used, the amount of iron precursor and the reaction time. Compared with conventional synthesis methods such as thermal decomposition or co-precipitation, this process yields nanoparticles with a narrow particle size distribution in a simple, reproducible and cost effective manner without the need for an inert atmosphere. For example, IONPs with a diameter of ca. 8 nm could be made in a reproducible manner and with good crystallinity as evidenced by X-ray diffraction analysis and high saturation magnetization value (84.5 emu g(-1)). The surface of the IONPs could be tailored post synthesis with two different ligands which provided functionality and stability in water and phosphate buffer saline (PBS). Their potential as a magnetic resonance imaging (MRI) contrast agent was confirmed as they exhibited high r1 and r2 relaxivities of 7.95 mM(-1) s(-1) and 185.58 mM(-1) s(-1) respectively at 1.4 T. Biocompatibility and viability of IONPs in primary human mesenchymal stem cells (hMSCs) was studied and confirmed

The effects of exposure to a rotating environment /10 rpm/ on four aviators for a period of twelve days

Motion sickness studies of aviators exposed to rotating environment - Aerospace medicin

Susceptibility to weathering damage and oxidative stress on soybean seeds with different lignin contents in the seed coat.

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Macroscopic quantum fluctuations in noise-sustained optical patterns

We investigate quantum effects in pattern formation for a degenerate optical parametric oscillator with walk-off. This device has a convective regime in which macroscopic patterns are both initiated and sustained by quantum noise. Familiar methods based on linearization about a pseudoclassical field fail in this regime and new approaches are required. We employ a method in which the pump field is treated as a c-number variable but is driven by the c-number representation of the quantum subharmonic signal field. This allows us to include the effects of the fluctuations in the signal on the pump, which in turn act back on the signal. We find that the nonclassical effects, in the form of squeezing, survive just above the threshold of the convective regime. Further, above threshold, the macroscopic quantum noise suppresses these effects

Cooling of a mirror by radiation pressure

We describe an experiment in which a mirror is cooled by the radiation pressure of light. A high-finesse optical cavity with a mirror coated on a mechanical resonator is used as an optomechanical sensor of the Brownian motion of the mirror. A feedback mechanism controls this motion via the radiation pressure of a laser beam reflected on the mirror. We have observed either a cooling or a heating of the mirror, depending on the gain of the feedback loop.Comment: 4 pages, 6 figures, RevTe