11,958 research outputs found
THERMTRAJ: A FORTRAN program to compute the trajectory and gas film temperatures of zero pressure balloons
A FORTRAN computer program called THERMTRAJ is presented which can be used to compute the trajectory of high altitude scientific zero pressure balloons from launch through all subsequent phases of the balloon flight. In addition, balloon gas and film temperatures can be computed at every point of the flight. The program has the ability to account for ballasting, changes in cloud cover, variable atmospheric temperature profiles, and both unconditional valving and scheduled valving of the balloon gas. The program was verified for an extensive range of balloon sizes (from 0.5 to 41.47 million cubic feet). Instructions on program usage, listing of the program source deck, input data and printed and plotted output for a verification case are included
A unified thermal and vertical trajectory model for the prediction of high altitude balloon performance
A computer model for the prediction of the trajectory and thermal behavior of zero-pressure high altitude balloon was developed. In accord with flight data, the model permits radiative emission and absorption of the lifting gas and daytime gas temperatures above that of the balloon film. It also includes ballasting, venting, and valving. Predictions obtained with the model are compared with flight data from several flights and newly discovered features are discussed
Majorization criterion for distillability of a bipartite quantum state
Bipartite quantum states are classified into three categories: separable
states, bound entangled states, and free entangled states. It is of great
importance to characterize these families of states for the development of
quantum information science. In this paper, I show that the separable states
and the bound entangled states have a common spectral property. More precisely,
I prove that for undistillable -- separable and bound entangled -- states, the
eigenvalue vector of the global system is majorized by that of the local
system. This result constitutes a new sufficient condition for distillability
of bipartite quantum states. This is achieved by proving that if a bipartite
quantum state satisfies the reduction criterion for distillability, then it
satisfies the majorization criterion for separability.Comment: 4 pages, no figures, REVTEX. A new lemma (Lemma 2) added. To appear
in Physical Review Letter
Wave Profile for Anti-force Waves with Maximum Possible Currents
In the theoretical investigation of the electrical breakdown of a gas, we apply a one-dimensional, steady state, constant velocity, three component fluid model and consider the electrons to be the main element in propagation of the wave. The electron gas temperature, and therefore the electron gas partial pressure, is considered to be large enough to provide the driving force. The wave is considered to have a shock front, followed by a thin dynamical transition region. Our set of electron fluid-dynamical equations consists of the equations of conservation of mass, momentum, and energy, plus the Poisson\u27s equation. The set of equations is referred to as the electron fluid dynamical equations; and a successful solution therefor must meet a set of acceptable physical conditions at the trailing edge of the wave. For breakdown waves with a significant current behind the shock front, modifications must be made to the set of electron fluid dynamical equations, as well as the shock condition on electron temperature. Considering existence of current behind the shock front, we have derived the shock condition on electron temperature, and for a set of experimentally measured wave speeds, we have been able to find maximum current values for which solutions to our set of electron velocity, electron temperature, and electron number density within the dynamical transition region of the wave
Quantum quench dynamics of the Bose-Hubbard model at finite temperatures
We study quench dynamics of the Bose-Hubbard model by exact diagonalization.
Initially the system is at thermal equilibrium and of a finite temperature. The
system is then quenched by changing the on-site interaction strength
suddenly. Both the single-quench and double-quench scenarios are considered. In
the former case, the time-averaged density matrix and the real-time evolution
are investigated. It is found that though the system thermalizes only in a very
narrow range of the quenched value of , it does equilibrate or relax well in
a much larger range. Most importantly, it is proven that this is guaranteed for
some typical observables in the thermodynamic limit. In order to test whether
it is possible to distinguish the unitarily evolving density matrix from the
time-averaged (thus time-independent), fully decoherenced density matrix, a
second quench is considered. It turns out that the answer is affirmative or
negative according to the intermediate value of is zero or not.Comment: preprint, 20 pages, 7 figure
Local and global statistical distances are equivalent on pure states
The statistical distance between pure quantum states is obtained by finding a
measurement that is optimal in a sense defined by Wootters. As such, one may
expect that the statistical distance will turn out to be different if the set
of possible measurements is restricted in some way. It nonetheless turns out
that if the restriction is to local operations and classical communication
(LOCC) on any multipartite system, then the statistical distance is the same as
it is without restriction, being equal to the angle between the states in
Hilbert space.Comment: 5 pages, comments welcom
Singular value decomposition and matrix reorderings in quantum information theory
We review Schmidt and Kraus decompositions in the form of singular value
decomposition using operations of reshaping, vectorization and reshuffling. We
use the introduced notation to analyse the correspondence between quantum
states and operations with the help of Jamiolkowski isomorphism. The presented
matrix reorderings allow us to obtain simple formulae for the composition of
quantum channels and partial operations used in quantum information theory. To
provide examples of the discussed operations we utilize a package for the
Mathematica computing system implementing basic functions used in the
calculations related to quantum information theory.Comment: 11 pages, no figures, see
http://zksi.iitis.pl/wiki/projects:mathematica-qi for related softwar
Minimum-error discrimination between mixed quantum states
We derive a general lower bound on the minimum-error probability for {\it
ambiguous discrimination} between arbitrary mixed quantum states with given
prior probabilities. When , this bound is precisely the well-known
Helstrom limit. Also, we give a general lower bound on the minimum-error
probability for discriminating quantum operations. Then we further analyze how
this lower bound is attainable for ambiguous discrimination of mixed quantum
states by presenting necessary and sufficient conditions related to it.
Furthermore, with a restricted condition, we work out a upper bound on the
minimum-error probability for ambiguous discrimination of mixed quantum states.
Therefore, some sufficient conditions are obtained for the minimum-error
probability attaining this bound. Finally, under the condition of the
minimum-error probability attaining this bound, we compare the minimum-error
probability for {\it ambiguously} discriminating arbitrary mixed quantum
states with the optimal failure probability for {\it unambiguously}
discriminating the same states.Comment: A further revised version, and some results have been adde
Madonna Study Group, Whole No. 1
https://ecommons.udayton.edu/imri_marian_philatelist/1000/thumbnail.jp
The Marian Philatelist, Whole No. 35
https://ecommons.udayton.edu/imri_marian_philatelist/1034/thumbnail.jp
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