558 research outputs found
Response of the geomagnetic activity index Kp to the interplanetary magnetic field
Response of geomagnetic activity index to interplanetary magnetic fiel
A model of interplanetary and coronal magnetic fields
Model of interplanetary and solar magnetic field structure above photosphere using Green function solution to Maxwell equation
A physical mechanism for the prediction of the sunspot number during solar cycle 21
On physical grounds it is suggested that the sun's polar field strength near a solar minimum is closely related to the following cycle's solar activity. Four methods of estimating the sun's polar magnetic field strength near solar minimum are employed to provide an estimate of cycle 21's yearly mean sunspot number at solar maximum of 140 plus or minus 20. This estimate is considered to be a first order attempt to predict the cycle's activity using one parameter of physical importance
Quantum mutual entropy for Jaynes-Cummings model
The dynamics of an atom on the Jaynes-Cummings model has been studied by an
atomic inversion, von Neumann entropy and so on. In this letter, we will treat
the Jaynes-Cummings model as a problem in non-equilibrium statistical mechanics
and apply quantum mutual entropy to study the irreversible dynamics of a state
for the atom on this model.Comment: RevTeX, 4 pages with a figure(eps file), submitted to Physical Review
Letter
Lazy states: sufficient and necessary condition for zero quantum entropy rates under any coupling to the environment
We find the necessary and sufficient conditions for the entropy rate of the
system to be zero under any system-environment Hamiltonian interaction. We call
the class of system-environment states that satisfy this condition lazy states.
They are a generalization of classically correlated states defined by quantum
discord, but based on projective measurements of any rank. The concept of lazy
states permits the construction of a protocol for detecting global quantum
correlations using only local dynamical information. We show how quantum
correlations to the environment provide bounds to the entropy rate, and how to
estimate dissipation rates for general non-Markovian open quantum systems.Comment: 4 page
Trap Target Studies
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
A separability criterion for density operators
We give a necessary and sufficient condition for a mixed quantum mechanical
state to be separable. The criterion is formulated as a boundedness condition
in terms of the greatest cross norm on the tensor product of trace class
operators.Comment: REVTeX, 5 page
Solar Polar Fields During Cycles 21 --- 23: Correlation with Meridional Flows
We have examined polar magnetic fields for the last three solar cycles,
{}, cycles 21, 22 and 23 using NSO Kitt Peak synoptic magnetograms.
In addition, we have used SoHO/MDI magnetograms to derive the polar fields
during cycle 23. Both Kitt Peak and MDI data at high latitudes
(78--90) in both solar hemispheres show a significant
drop in the absolute value of polar fields from the late declining phase of the
solar cycle 22 to the maximum of the solar cycle 23. We find that long term
changes in the absolute value of the polar field, in cycle 23, is well
correlated with changes in meridional flow speeds that have been reported
recently. We discuss the implication of this in influencing the extremely
prolonged minimum experienced at the start of the current cycle 24 and in
forecasting the behaviour of future solar cycles.Comment: 4 Figures 11 pages; Revised version under review in Solar Physic
Large-scale horizontal flows in the solar photosphere V: Possible evidence for the disconnection of bi-polar sunspot groups from their magnetic roots
In a recent paper (Svanda et al., 2008, A&A 477, 285) we pointed out that,
based on the tracking of Doppler features in the full-disc MDI Dopplergrams,
the active regions display two dynamically different regimes. We speculated
that this could be a manifestation of the sudden change in the active regions
dynamics, caused by the dynamic disconnection of sunspots from their magnetic
roots as proposed by Schuessler & Rempel (2005, A&A 441, 337). Here we
investigate the dynamic behaviour of the active regions recorded in the
high-cadence MDI data over the last solar cycle in order to confirm the
predictions in the Schuessler's & Rempel's paper. We find that, after drastic
reduction of the sample, which is done to avoid disturbing effects, a large
fraction of active regions displays a sudden decrease in the rotation speed,
which is compatible with the mechanism of the dynamic disconnection of sunspots
from their parental magnetic structures.Comment: 11 pages, 9 figures, 1 table; accepted in Astronomy & Astrophysic
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