2,044 research outputs found
Distributed entanglement induced by dissipative bosonic media
We describe a scheme with analytic result that allows to generate
steady-state entanglement for two atoms over a dissipative bosonic medium. The
resonant coupling between the mediating bosonic mode and cavity modes produces
three collective atomic decay channels. This dissipative dynamics, together
with the unitary process induced by classical microwave fields, drives the two
atoms to the symmetric or asymmetric entangled steady state conditional upon
the choice of the phases of the microwave fields. The effects on the
steady-state entanglement of off-resonance mediating bosonic modes are
analyzed. The entanglement can be obtained with high fidelity regardless of the
initial state and there is a linear relation in the scaling of the fidelity
with the cooperativity parameter. The fidelity is insensitive to the
fluctuation of the Rabi frequencies of the classical driving fields.Comment: to appear in Europhysics Letter
5 GHz TMRT observations of 71 pulsars
We present integrated pulse profiles at 5~GHz for 71 pulsars, including eight
millisecond pulsars (MSPs), obtained using the Shanghai Tian Ma Radio Telescope
(TMRT). Mean flux densities and pulse widths are measured. For 19 normal
pulsars and one MSP, these are the first detections at 5~GHz and for a further
19, including five MPSs, the profiles have a better signal-to-noise ratio than
previous observations. Mean flux density spectra between 400~MHz and 9~GHz are
presented for 27 pulsars and correlations of power-law spectral index are found
with characteristic age, radio pseudo-luminosity and spin-down luminosity. Mode
changing was detected in five pulsars. The separation between the main pulse
and interpulse is shown to be frequency independent for six pulsars but a
frequency dependence of the relative intensity of the main pulse and interpulse
is found. The frequency dependence of component separations is investigated for
20 pulsars and three groups are found: in seven cases the separation between
the outmost leading and trailing components decreases with frequency, roughly
in agreement with radius-to-frequency mapping; in eleven cases the separation
is nearly constant; in the remain two cases the separation between the outmost
components increases with frequency. We obtain the correlations of pulse widths
with pulsar period and estimate the core widths of 23 multi-component profiles
and conal widths of 17 multi-component profiles at 5.0~GHz using Gaussian
fitting and discuss the width-period relationship at 5~GHz compared with the
results at at 1.0~GHz and 8.6~GHz.Comment: 46 pages, 14 figures, 8 Tables, accepted by Ap
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