1,460 research outputs found
Two-particle interference in standard and Bohmian quantum mechanics
The compatibility of standard and Bohmian quantum mechanics has recently been
challenged in the context of two-particle interference, both from a theoretical
and an experimental point of view. We analyze different setups proposed and
derive corresponding exact forms for Bohmian equations of motion. The equations
are then solved numerically, and shown to reproduce standard quantum-mechanical
results.Comment: Minor corrections, 2 references added, version to appear in J. Phys.
Review of recent experimental progresses in Foundations of Quantum Mechanics and Quantum Information obtained in Parametric Down Conversion Experiments at IENGF
We review some recent experimental progresses concerning Foundations of
Quantum Mechanics and Quantum Information obtained in Quantum Optics Laboratory
"Carlo Novero" at IENGF.
More in details, after a short presentation of our polarization entangled
photons source (based on precise superposition of two Type I PDC emission) and
of the results obtained with it, we describe an innovative double slit
experiment where two degenerate photons produced by PDC are sent each to a
specific slit. Beyond representing an interesting example of relation between
visibility of interference and "welcher weg" knowledge, this configuration has
been suggested for testing de Broglie-Bohm theory against Standard Quantum
Mechanics. Our results perfectly fit SQM results, but disagree with dBB
predictions.
Then, we discuss a recent experiment addressed to clarify the issue of which
wave-particle observables are really to be considered when discussing wave
particle duality. This experiments realises the Agarwal et al. theoretical
proposal, overcoming limitations of a former experiment.
Finally, we hint to the realization of a high-intensity
high-spectral-selected PDC source to be used for quantum information studies
Endogenous Quasicycles and Stochastic Coherence in a Closed Endemic Model
We study the role of demographic fluctuations in typical endemics as
exemplified by the stochastic SIRS model. The birth-death master equation of
the model is simulated using exact numerics and analysed within the linear
noise approximation. The endemic fixed point is unstable to internal
demographic noise, and leads to sustained oscillations. This is ensured when
the eigenvalues () of the linearised drift matrix are complex, which
in turn, is possible only if detailed balance is violated. In the oscillatory
state, the phases decorrelate asymptotically, distinguishing such oscillations
from those produced by external periodic forcing. These so-called quasicycles
are of sufficient strength to be detected reliably only when the ratio
is of order unity. The coherence or regularity of
these oscillations show a maximum as a function of population size, an effect
known variously as stochastic coherence or coherence resonance. We find that
stochastic coherence can be simply understood as resulting from a non-monotonic
variation of with population size. Thus, within the
linear noise approximation, stochastic coherence can be predicted from a purely
deterministic analysis. The non-normality of the linearised drift matrix,
associated with the violation of detailed balance, leads to enhanced
fluctuations in the population amplitudes.Comment: 21 pages, 8 figure
Experimental tests of hidden variable theories from dBB to Stochastic Electrodynamics
In this paper we present some of our experimental results on testing hidden
variable theories, which range from Bell inequalities measurements to a
conclusive test of stochastic electrodynamics
Lorentz Invariant Superluminal Tunneling
It is shown that superluminal optical signalling is possible without
violating Lorentz invariance and causality via tunneling through photonic band
gaps in inhomogeneous dielectrics of a special kind.Comment: 10 pages revtex, no figure, more discussions added, submitted to
Phys. Rev.
Profiling of VEGFs and VEGFRs as Prognostic Factors in Soft Tissue Sarcoma: VEGFR-3 Is an Independent Predictor of Poor Prognosis
BACKGROUND: In non-gastrointestinal stromal tumor soft tissue sarcoma (non-GIST STS) optimal treatment is surgery with wide resection margins. Vascular endothelial growth factors (VEGFs) and receptors (VEGFRs) are known to be key players in the initiation of angiogenesis and lymphangiogenesis. This study investigates the prognostic impact of VEGFs and VEGFRs in non-GIST STS with wide and non-wide resection margins. METHODS: Tumor samples from 249 patients with non-GIST STS were obtained and tissue microarrays were constructed for each specimen. Immunohistochemistry was used to evaluate the expressions of VEGF-A, -C and -D and VEGFR-1, -2 and -3. RESULTS: In the univariate analyses, VEGF-A (P=0.040) in the total material, and VEGF-A (P=0.018), VEGF-C (P=0.025) and VEGFR-3 (P=0.027) in the subgroup with wide resection margins, were significant negative prognostic indicators of disease-specific survival (DSS). In the multivariate analysis, high expression of VEGFR-3 (P=0.042, HR=1.907, 95% CI 1.024-3.549) was an independent significant negative prognostic marker for DSS among patients with wide resection margins. CONCLUSION: VEGFR-3 is a strong and independent negative prognostic marker for non-GIST STSs with wide resection margins
Geometric phase distributions for open quantum systems
In an open system, the geometric phase should be described by a distribution.
We show that a geometric phase distribution for open system dynamics is in
general ambiguous, but the imposition of reasonable physical constraints on the
environment and its coupling with the system yields a unique geometric phase
distribution that applies even for mixed states, non-unitary dynamics, and
non-cyclic evolutions.Comment: Some minor revisions, references update
- …