17,887 research outputs found
Thermal Bremsstrahlung Radiation in a Two-Temperature Plasma
In the normal one-temperature plasma the motion of ions is usually neglected
when calculating the Bremsstrahlung radiation of the plasma. Here we calculate
the Bremsstrahlung radiation of a two-temperature plasma by taking into account
of the motion of ions. Our results show that the total radiation power is
always lower if the motion of ions is considered. We also apply the
two-temperature Bremsstrahlung radiation mechanism for an analytical
Advection-Dominated Accretion Flow (ADAF) model; we find the two-temperature
correction to the total Bremsstrahlung radiation for ADAF is negligible.Comment: 5 pages, 4 figures, accepted for publication in CHJAA. Some
discussions and references adde
A discrete time-dependent method for metastable atoms in intense fields
The full-dimensional time-dependent Schrodinger equation for the electronic
dynamics of single-electron systems in intense external fields is solved
directly using a discrete method.
Our approach combines the finite-difference and Lagrange mesh methods. The
method is applied to calculate the quasienergies and ionization probabilities
of atomic and molecular systems in intense static and dynamic electric fields.
The gauge invariance and accuracy of the method is established. Applications to
multiphoton ionization of positronium and hydrogen atoms and molecules are
presented. At very high intensity above saturation threshold, we extend the
method using a scaling technique to estimate the quasienergies of metastable
states of the hydrogen molecular ion. The results are in good agreement with
recent experiments.Comment: 10 pages, 9 figure, 4 table
Full one-loop electroweak radiative corrections to single photon production in e+e-
Large scale calculation for the radiative corrections required for the
current and future collider experiments can be done automatically using the
GRACE-LOOP system. Here several results for e+e- --> 3-body processes are
presented including e+e- --> e+e-H and e+e- --> nu nubar gamma.Comment: 5 pages, contribution to ACAT03(Dec. 2003
Non-Markovian entanglement dynamics in coupled superconducting qubit systems
We theoretically analyze the entanglement generation and dynamics by coupled
Josephson junction qubits. Considering a current-biased Josephson junction
(CBJJ), we generate maximally entangled states. In particular, the entanglement
dynamics is considered as a function of the decoherence parameters, such as the
temperature, the ratio between the reservoir cutoff
frequency and the system oscillator frequency , % between
the characteristic frequency of the %quantum system of interest, and
the cut-off frequency of %Ohmic reservoir and the energy levels
split of the superconducting circuits in the non-Markovian master equation. We
analyzed the entanglement sudden death (ESD) and entanglement sudden birth
(ESB) by the non-Markovian master equation. Furthermore, we find that the
larger the ratio and the thermal energy , the shorter the
decoherence. In this superconducting qubit system we find that the entanglement
can be controlled and the ESD time can be prolonged by adjusting the
temperature and the superconducting phases which split the energy
levels.Comment: 13 pages, 3 figure
The mass of the black hole in RE J1034+396
The black hole mass measurement in active galaxies is a challenge,
particularly in sources where the reverberation method cannot be applied. We
aim to determine the black hole mass in a very special object, RE J1034+396,
one of the two AGN with QPO oscillations detected in X-rays, and a single
bright AGN with optical band totally dominated by starlight. We fit the stellar
content using the code starlight, and the broad band disk contribution to
optical/UV/X-ray emission is modeled with optxagnf. We also determine the black
hole mass using several other independent methods. Various methods give
contradictory results. Most measurements of the blacc hole mass are in the
range 1.e6-1.e7 Msun, and the measurements based on dynamics give higher values
than measurements based on Hbeta and Mg II emission lines.Comment: A&A, in pres
Persistent single-photon production by tunable on-chip micromaser with a superconducting quantum circuit
We propose a tunable on-chip micromaser using a superconducting quantum
circuit (SQC). By taking advantage of externally controllable state
transitions, a state population inversion can be achieved and preserved for the
two working levels of the SQC and, when needed, the SQC can generate a single
photon. We can regularly repeat these processes in each cycle when the
previously generated photon in the cavity is decaying, so that a periodic
sequence of single photons can be produced persistently. This provides a
controllable way for implementing a persistent single-photon source on a
microelectronic chip.Comment: 8 pages, 4 figure
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