20,890 research outputs found
Quantum clocks observe classical and quantum time dilation
At the intersection of quantum theory and relativity lies the possibility of
a clock experiencing a superposition of proper times. We consider quantum
clocks constructed from the internal degrees of relativistic particles that
move through curved spacetime. The probability that one clock reads a given
proper time conditioned on another clock reading a different proper time is
derived. From this conditional probability distribution, it is shown that when
the center-of-mass of these clocks move in localized momentum wave packets they
observe classical time dilation. We then illustrate a quantum correction to the
time dilation observed by a clock moving in a superposition of localized
momentum wave packets that has the potential to be observed in experiment. The
Helstrom-Holevo lower bound is used to derive a proper time-energy/mass
uncertainty relation.Comment: Updated to match published versio
PERFECT SUBSTITUTES: A NOTE ON THE ALCHIAN-ALLEN HYPOTHESIS
Alchian and Allen hypothesized that a country will export high rather than low quality goods. Here we show that if the inherent attributes of the commodities are identical the country will only export the high-quality good.transport costs, patterns of trade, product quality, International Relations/Trade, F1,
Communication between inertial observers with partially correlated reference frames
In quantum communication protocols the existence of a shared reference frame
between two spatially separated parties is normally presumed. However, in many
practical situations we are faced with the problem of misaligned reference
frames. In this paper, we study communication between two inertial observers
who have partial knowledge about the Lorentz transformation that relates their
frames of reference. Since every Lorentz transformation can be decomposed into
a pure boost followed by a rotation, we begin by analysing the effects on
communication when the parties have partial knowledge about the transformation
relating their frames, when the transformation is either a rotation or pure
boost. This then enables us to investigate how the efficiency of communication
is affected due to partially correlated inertial reference frames related by an
arbitrary Lorentz transformation. Furthermore, we show how the results of
previous studies where reference frames are completely uncorrelated are
recovered from our results in appropriate limits.Comment: 9 pages, 3 figures, typos corrected, figures update
Studies In The Genus Mycena. I.
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141539/1/ajb205071.pd
Spacetime structure and vacuum entanglement
We study the role that both vacuum fluctuations and vacuum entanglement of a
scalar field play in identifying the spacetime topology, which is not
prescribed from first principles---neither in general relativity or quantum
gravity. We analyze how the entanglement and observable correlations acquired
between two particle detectors are sensitive to the spatial topology of
spacetime. We examine the detector's time evolution to all orders in
perturbation theory and then study the phenomenon of vacuum entanglement
harvesting in Minkowski spacetime and two flat topologically distinct
spacetimes constructed from identifications of the Minkowski space. We show
that, for instance, if the spatial topology induces a preferred direction, this
direction may be inferred from the dependence of correlations between the two
detectors on their orientation. We therefore show that vacuum fluctuations and
vacuum entanglement harvesting makes it, in principle, possible to distinguish
spacetimes with identical local geometry that differ only in their topology
The application of remotely sensed data in support of emergency rehabilitation of wildfire-damage areas
The depth, texture, and water holding capacity of the soil before the fire in the Bridge Creek area of Deschutes National Forest (1979) were determined from available aerial photography and LANDSAT MSS digital data. Three days after the fire was out, complete coverage of the burned area was acquired on 35 mm color infrared film from a near vertical or low oblique perspective. These photographs were used in assessing the condition of vegetation, and in predicting the likelihood of survival. Negatives from vertical natural photography obtained during the same flight were used to produce 3R prints from which large scale mosaics of the entire burned area were obtained. LANDSAT MSS data obtained on the day the fire was under control were used to evaluate vegetative vigor (by calculating a band 7/band 5 ratio value for each spectral class) and to determine the boundary between altered and unaltered land
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