844 research outputs found
Existence of the Bogoliubov S(g) operator for the quantum field theory
We prove the existence of the Bogoliubov S(g) operator for the
quantum field theory for coupling functions of compact support in space and
time. The construction is nonperturbative and relies on a theorem of
Kisy\'nski. It implies almost automatically the properties of unitarity and
causality for disjoint supports in the time variable.Comment: LaTeX, 24 pages, minor modifications, typos correcte
The Escape Problem in a Classical Field Theory With Two Coupled Fields
We introduce and analyze a system of two coupled partial differential
equations with external noise. The equations are constructed to model
transitions of monovalent metallic nanowires with non-axisymmetric intermediate
or end states, but also have more general applicability. They provide a rare
example of a system for which an exact solution of nonuniform stationary states
can be found. We find a transition in activation behavior as the interval
length on which the fields are defined is varied. We discuss several
applications to physical problems.Comment: 24 page
On the distribution of the Wigner time delay in one-dimensional disordered systems
We consider the scattering by a one-dimensional random potential and derive
the probability distribution of the corresponding Wigner time delay. It is
shown that the limiting distribution is the same for two different models and
coincides with the one predicted by random matrix theory. It is also shown that
the corresponding stochastic process is given by an exponential functional of
the potential.Comment: 11 pages, four references adde
Room-Temperature Quantum Emitter in Aluminum Nitride
A device that is able to produce single photons is a fundamental building
block for a number of quantum technologies. Significant progress has been made
in engineering quantum emission in the solid state, for instance, using
semiconductor quantum dots as well as defect sites in bulk and two-dimensional
materials. Here we report the discovery of a room-temperature quantum emitter
embedded deep within the band gap of aluminum nitride. Using spectral,
polarization, and photon-counting time-resolved measurements we demonstrate
bright ( counts per second), pure (), and polarized
room-temperature quantum light emission from color centers in this commercially
important semiconductor
Universality of the Wigner time delay distribution for one-dimensional random potentials
We show that the distribution of the time delay for one-dimensional random
potentials is universal in the high energy or weak disorder limit. Our
analytical results are in excellent agreement with extensive numerical
simulations carried out on samples whose sizes are large compared to the
localisation length (localised regime). The case of small samples is also
discussed (ballistic regime). We provide a physical argument which explains in
a quantitative way the origin of the exponential divergence of the moments. The
occurence of a log-normal tail for finite size systems is analysed. Finally, we
present exact results in the low energy limit which clearly show a departure
from the universal behaviour.Comment: 4 pages, 3 PostScript figure
A closer look at the uncertainty relation of position and momentum
We consider particles prepared by the von Neumann-L\"uders projection. For
those particles the standard deviation of the momentum is discussed. We show
that infinite standard deviations are not exceptions but rather typical. A
necessary and sufficient condition for finite standard deviations is given.
Finally, a new uncertainty relation is derived and it is shown that the latter
cannot be improved.Comment: 3 pages, introduction shortened, content unchange
Subsurface S-type Granitoid Identification Based on Gravity and Seismic Tomography Models in Pacitan, East Java
Granitoid outcrop has been observed in Montongan, Tulakan Subdistrict, Pacitan District, East Java. Geochemically, granitoid shows peralluminous S-type granitoid which consists of comparable plagioclase and potassium feldspar leading to adamelite and granodiorite variety with andalusite, fine size corundum and cordierite inside. These modal minerals are consistent with its bulk chemical analysis result that shows alumina rich rock. Highly weathered spotted pinkish soil with remaining quartz gravels characterizes its surface. Lateritic pink soil up to more than 25 meters thick covers the granitoid body and this feature is indicative to locate its surface distribution, while its subsurface distribution is remain uncertain. The research aimed to identify granitoid subsurface distribution. To identify the subsurface body, gravity and seismic tomography models were used. According gravity model, the pluton body is 5 km wide which is rootless downward and seems extends eastward. Meanwhile, the north-south seismic tomographic model across Pacitan Region indicates dense solid body override the recent Java subduction zone. The body is assumed to have correlation with surface granitic rock. It supports an idea that there is a micro continent trapped beneath Southern Mountain of East Java
On the Global Existence of Bohmian Mechanics
We show that the particle motion in Bohmian mechanics, given by the solution
of an ordinary differential equation, exists globally: For a large class of
potentials the singularities of the velocity field and infinity will not be
reached in finite time for typical initial values. A substantial part of the
analysis is based on the probabilistic significance of the quantum flux. We
elucidate the connection between the conditions necessary for global existence
and the self-adjointness of the Schr\"odinger Hamiltonian.Comment: 35 pages, LaTe
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