Exact Boson Sampling using Gaussian continuous variable measurements

BosonSampling is a quantum mechanical task involving Fock basis state preparation and detection and evolution using only linear interactions. A classical algorithm for producing samples from this quantum task cannot be efficient unless the polynomial hierarchy of complexity classes collapses, a situation believe to be highly implausible. We present method for constructing a device which uses Fock state preparations, linear interactions and Gaussian continuous-variable measurements for which one can show exact sampling would be hard for a classical algorithm in the same way as Boson Sampling. The detection events used from this arrangement does not allow a similar conclusion for the classical hardness of approximate sampling to be drawn. We discuss the details of this result outlining some specific properties that approximate sampling hardness requires

Resolving the electron temperature discrepancies in HII Regions and Planetary Nebulae: kappa-distributed electrons

The measurement of electron temperatures and metallicities in H ii regions and Planetary Nebulae (PNe) has-for several decades-presented a problem: results obtained using different techniques disagree. What it worse, they disagree consistently. There have been numerous attempts to explain these discrepancies, but none has provided a satisfactory solution to the problem. In this paper, we explore the possibility that electrons in H ii regions and PNe depart from a Maxwell-Boltzmann equilibrium energy distribution. We adopt a "kappa-distribution" for the electron energies. Such distributions are widely found in Solar System plasmas, where they can be directly measured. This simple assumption is able to explain the temperature and metallicity discrepancies in H ii regions and PNe arising from the different measurement techniques. We find that the energy distribution does not need to depart dramatically from an equilibrium distribution. From an examination of data from Hii regions and PNe it appears that kappa ~ 10 is sufficient to encompass nearly all objects. We argue that the kappa-distribution offers an important new insight into the physics of gaseous nebulae, both in the Milky Way and elsewhere, and one that promises significantly more accurate estimates of temperature and metallicity in these regions.Comment: 16 pages, 11 figures, 2 tables, published in Ap

Conditional Production of Superpositions of Coherent States with Inefficient Photon Detection

It is shown that a linear superposition of two macroscopically distinguishable optical coherent states can be generated using a single photon source and simple all-optical operations. Weak squeezing on a single photon, beam mixing with an auxiliary coherent state, and photon detecting with imperfect threshold detectors are enough to generate a coherent state superposition in a free propagating optical field with a large coherent amplitude ($\alpha>2$) and high fidelity ($F>0.99$). In contrast to all previous schemes to generate such a state, our scheme does not need photon number resolving measurements nor Kerr-type nonlinear interactions. Furthermore, it is robust to detection inefficiency and exhibits some resilience to photon production inefficiency.Comment: Some important new results added, to appear in Phys.Rev.A (Rapid Communication

The impact of 5-hydroxytryptamine-receptor antagonists on chemotherapy treatment adherence, treatment delay, and nausea and vomiting.

PurposeTo determine the incidence of chemotherapy-induced nausea/vomiting (CINV) and chemotherapy treatment delay and adherence among patients receiving palonosetron versus other 5-hydroxytryptamine receptor antagonist (5-HT3 RA) antiemetics.Materials and methodsThis retrospective claims analysis included adults with primary malignancies who initiated treatment consisting of single-day intravenous highly emetogenic chemotherapy (HEC) or moderately EC (MEC) regimens. Treatment delay was defined as a gap in treatment at least twice the National Comprehensive Cancer Network-specified cycle length, specific to each chemotherapy regimen. Treatment adherence was determined by the percentage of patients who received the regimen-specific recommended number of chemotherapy cycles within the recommended time frame.ResultsWe identified 1,832 palonosetron and 2,387 other 5-HT3 RA ("other") patients who initiated HEC therapy, and 1,350 palonosetron users and 1,379 patients on other antiemetics who initiated MEC therapy. Fewer patients receiving palonosetron experienced CINV versus other (HEC, 27.5% versus 32.2%, P=0.0011; MEC, 36.1% versus 41.7%, P=0.0026), and fewer treatment delays occurred among patients receiving palonosetron versus other (HEC, 3.2% versus 6.0%, P<0.0001; MEC, 17.0% versus 26.8%, P<0.0001). Compared with the other cohort, patients receiving palonosetron were significantly more adherent to the index chemotherapy regimen with respect to the recommended time frame (HEC, 74.7% versus 69.7%, P=0.0004; MEC, 43.1% versus 37.3%, P=0.0019) and dosage (HEC, 27.3% versus 25.8%, P=0.0004; MEC, 15.0% versus 12.6%, P=0.0019).ConclusionPalonosetron more effectively reduced occurrence of CINV in patients receiving HEC or MEC compared with other agents in this real-world setting. Additionally, patients receiving palonosetron had better adherence and fewer treatment delays than patients receiving other 5-HT3 RAs

Dusty, Radiation Pressure Dominated Photoionization. II. Multi-Wavelength Emission Line Diagnostics for Narrow Line Regions

Seyfert narrow line region (NLR) emission line ratios are remarkably uniform, displaying only ~0.5 dex variation between galaxies, and even less within an individual object. Previous photoionization and shock models of this region were unable to explain this observation without the introduction of arbitrary assumptions or additional parameters. Dusty, radiation pressure dominated photoionization models provide a simple physical mechanism which can reproduce this spectral uniformity between different objects. In the first paper of this series we described this model and its implementation in detail, as well as presenting grids of model emission lines and examining the model structures. Here we explore these models further, demonstrating their ability to reproduce the observed Seyfert line ratios on standard line diagnostic diagrams in both the optical and UV. We also investigate the effects that the variation of metallicity, density and ionizing spectrum have upon both the new paradigm and the standard photoionization models used hitherto. Along with the standard diagnostic diagrams we provide several new diagnostic diagrams in the UV, Optical and IR. These new diagrams can provide further tests of the dusty, radiation pressure photoionization paradigm as well as being used as diagnostics of the metallicity, density and ionizing spectrum of the emission line clouds.Comment: Accepted by ApJS, full pdf including figures can be obtained at http://www.mso.anu.edu.au/~bgroves/Papers/ApJS2.pd

Photon Sorting, Efficient Bell Measurements and a Deterministic CZ Gate using a Passive Two-level Nonlinearity

Although the strengths of optical non-linearities available experimentally have been rapidly increasing in recent years, significant challenges remain to using such non-linearities to produce useful quantum devices such as efficient optical Bell state analysers or universal quantum optical gates. Here we describe a new approach that avoids the current limitations by combining strong non-linearities with active Gaussian operations in efficient protocols for Bell state analysers and Controlled-Sign gates