1,791 research outputs found
Photon echo quantum RAM integration in quantum computer
We have analyzed an efficient integration of the multi-qubit echo quantum
memory into the quantum computer scheme on the atomic resonant ensembles in
quantum electrodynamics cavity. Here, one atomic ensemble with controllable
inhomogeneous broadening is used for the quantum memory node and other atomic
ensembles characterized by the homogeneous broadening of the resonant line are
used as processing nodes. We have found optimal conditions for efficient
integration of multi-qubit quantum memory modified for this analyzed physical
scheme and we have determined a specified shape of the self temporal modes
providing a perfect reversible transfer of the photon qubits between the
quantum memory node and arbitrary processing nodes. The obtained results open
the way for realization of full-scale solid state quantum computing based on
using the efficient multi-qubit quantum memory.Comment: 13 pages, 5 figure
Stellar kinematics of X-ray bright massive elliptical galaxies
We discuss a simple and fast method for estimating masses of early-type
galaxies from optical data and compare the results with X-ray derived masses.
The optical method relies only on the most basic observables such as the
surface brightness and the line-of-sight velocity dispersion
profiles and provides an anisotropy-independent estimate of the
galaxy circular speed . The mass-anisotropy degeneracy is effectively
overcome by evaluating at a characteristic radius defined
from {\it local} properties of observed profiles. The sweet radius is expected to lie close to , where , and not
far from the effective radius . We apply the method to a sample of
five X-ray bright elliptical galaxies observed with the 6-m telescope BTA-6 in
Russia. We then compare the optical -estimate with the X-ray derived
value, and discuss possible constraints on the non-thermal pressure in the hot
gas and configuration of stellar orbits. We find that the average ratio of the
optical -estimate to the X-ray one is equal to with
scatter, i.e. there is no evidence for the large non-thermal pressure
contribution in the gas at . From analysis of the Lick
indices H, Mgb, Fe5270 and Fe5335, we calculate the mass of the stellar
component within the sweet radius. We conclude that a typical dark matter
fraction inside in the sample galaxies is for the
Salpeter IMF and for the Kroupa IMF.Comment: accepted for publication in MNRA
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