25,875 research outputs found
Three path interference using nuclear magnetic resonance: a test of the consistency of Born's rule
The Born rule is at the foundation of quantum mechanics and transforms our
classical way of understanding probabilities by predicting that interference
occurs between pairs of independent paths of a single object. One consequence
of the Born rule is that three way (or three paths) quantum interference does
not exist. In order to test the consistency of the Born rule, we examine
detection probabilities in three path intereference using an ensemble of
spin-1/2 quantum registers in liquid state nuclear magnetic resonance (LSNMR).
As a measure of the consistency, we evaluate the ratio of three way
interference to two way interference. Our experiment bounded the ratio to the
order of , and hence it is consistent with Born's rule.Comment: 11 pages, 4 figures; Improved presentation of figures 1 and 4,
changes made in section 2 to better describe the experiment, minor changes
throughout, and added several reference
Nuclear isotope thermometry
We discuss different aspects which could influence temperatures deduced from
experimental isotopic yields in the multifragmentation process. It is shown
that fluctuations due to the finite size of the system and distortions due to
the decay of hot primary fragments conspire to blur the temperature
determination in multifragmentation reactions. These facts suggest that caloric
curves obtained through isotope thermometers, which were taken as evidence for
a first-order phase transition in nuclear matter, should be investigated very
carefully.Comment: 9 pages, 7 figure
Two dimensional XXZ-Ising model on square-hexagon lattice
We study a two dimensional XXZ-Ising on square-hexagon (4-6) lattice with
spin-1/2. The phase diagram of the ground state energy is discussed, shown two
different ferrimagnetic states and two type of antiferromagnetic states, beside
of a ferromagnetic state. To solve this model, it could be mapped into the
eight-vertex model with union jack interaction term. Imposing exact solution
condition we find the region where the XXZ-Ising model on 4-6 lattice have
exact solutions with one free parameter, for symmetric eight-vertex model
condition. In this sense we explore the properties of the system and analyze
the competition of the interaction parameters providing the region where it has
an exact solution. However the present model does not satisfy the \textit{free
fermion} condition, unless for a trivial situation. Even so we are able to
discuss their critical points region, when the exactly solvable condition is
ignored.Comment: 5 pages, 5 figure
Numerical Computation of Finite Size Scaling Functions: An Alternative Approach to Finite Size Scaling
Using single cluster flip Monte Carlo simulations we accurately determine new
finite size scaling functions which are expressed only in terms the variable , where is the correlation length in a finite system of
size . Data for the d=2 and d=3 Ising models, taken at different
temperatures and for different size lattices, show excellent data collapse over
the entire range of scaling variable for susceptibility and correlation length.
From these finite size scaling functions we can estimate critical temperatures
and exponents with rather high accuracy even though data are not obtained
extremely close to the critical point. The bulk values of the renormalized
four-point coupling constant are accurately measured and show strong evidence
for hyperscaling.Comment: RevTex. 19 page
Scaling in Fracture and Refreezing of Sea Ice
Sea ice breaks up and regenerates rapidly during winter conditions in the
Arctic. Analyzing satellite data from the Kara Sea, we find that the average
ice floe size depends on weather conditions. Nevertheless, the frequency of
floes of size is a power law, , where ,
for less than approximately 100 . This scale-invariant behaviour
suggests a competition between fracture due to strains in the ice field and
refreezing of the fractures. A cellular model for this process gives results
consistent with observations.Comment: Physica A (in press
Dark Sector from Interacting Canonical and Non-Canonical Scalar Fields
In this work it is investigated general models with interactions between two
canonical scalar fields and between one non-canonical (tachyon-type) and one
canonical scalar field. The potentials and couplings to the gravity are
selected through the Noether symmetry approach. These general models are
employed to describe interactions between dark energy and dark matter, with the
fields being constrained by the astronomical data. The cosmological solutions
of some cases are compared with the observed evolution of the late Universe.Comment: 20 pages, 13 figures, correction of misprints in eqs. (4), (5), (43),
(44
Constraining non-minimally coupled tachyon fields by Noether symmetry
A model for a spatially flat homogeneous and isotropic Universe whose
gravitational sources are a pressureless matter field and a tachyon field
non-minimally coupled to the gravitational field is analyzed. Noether symmetry
is used to find the expressions for the potential density and for the coupling
function, and it is shown that both must be exponential functions of the
tachyon field. Two cosmological solutions are investigated: (i) for the early
Universe whose only source of the gravitational field is a non-minimally
coupled tachyon field which behaves as an inflaton and leads to an exponential
accelerated expansion and (ii) for the late Universe whose gravitational
sources are a pressureless matter field and a non-minimally coupled tachyon
field which plays the role of dark energy and is the responsible of the
decelerated-accelerated transition period.Comment: 11 pages, 5 figures. Version accepted for publication in Classical
and Quantum Gravit
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