12,320 research outputs found
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 () and high fidelity (). 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
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