750 research outputs found
Decoherence of tripartite states - a trapped ion coupled to an optical cavity
We investigate the non-dissipative decoherence of three qubit system obtained
by manipulating the state of a trapped two-level ion coupled to an optical
cavity. Modelling the environment as a set of noninteracting harmonic
oscillators, analytical expressions for the state operator of tripartite
composite system, the probability of generating maximally entangled GHZ state,
and the population inversion have been obtained. The pointer observable is the
energy of the isolated quantum system. Coupling to environment results in
exponential decay of off diagonal matrix elements of the state operator with
time as well as a phase decoherence of the component states.
Numerical calculations to examine the time evolution of GHZ state generation
probability and population inversion for different system environment coupling
strengths are performed. Using negativity as an entanglement measure and linear
entropy as a measure of mixedness, the entanglement dynamics of the tripartite
system in the presence of decoherence is analysed.Comment: Revised version, errors corrected and references added. 12 pages, 6
figures, Presented at ICSSUR May 2005, Besancon, Franc
Evaluation of air pollution tolerance index of certain plant species grown alongside Parwanoo to Solan National Highway-22 in Himachal Pradesh, India
The study examined the Air Pollution Tolerance Index (APTI) of selected plant species growing along national highway-22 from Parwanoo to Solan, falling in Solan district of Himachal Pradesh, India. Four species namely Grewiaoptiva, Toonaciliata, Melia azedarach and Woodfordia floribunda of uniform size, age, spread and common in occurrence on both sides of the highway are selected. Leaf samples were collected from selected spe-cies and used to estimate four physiological and biochemical parameters, namely; leaf relative water content (RWC), ascorbic acid content (AA), total leaf chlorophyll (TChl) and leaf extract pH were used to compute the APTI values. The trend of APTI recorded for various species was Melia azedarach (18.37) >Grewiaoptiva(8.77) >Woodfordia floribunda (7.43) >Toonaciliata(6.82). The APTI also varied with seasons of the year. The highest APTI was noticed in rainy followed by winter and summer season. The study indicated Melia azedarach as most tolerant and Toonaciliataas most sensitive species to air pollution
On the Performance Analysis of Wireless Receiver in Cascaded Fading Channel
In this paper, we provide a unified analysis for wireless system over cascaded fading channels modeled either by cascaded Nakagami-m or Weibull fading models. These cascade fading models are developed by the product of independent Nakagami-m or Weibull random variables, which are not necessary identically distributed. The performance measures such as amount of fading, average bit error rate, and signal outage are computed in this analysis. We first use the Padé approximation (PA) technique to find simple to evaluate rational expressions for the moment generating function (MGF) of output signal-to-noise ratio (SNR), unlike previously derived intricate expressions in terms of MeijerG function for cascaded Nakagami-m fading channel. Rational expressions for the MGF of the cascaded Weibull random variable are also computed to provide new set of performance results. Using these rational expressions, we analyze the performance of wireless receivers under a range of representative channel fading conditions using
both cascaded fading models. To verify the correctness of the proposed rational expression formulation numerical and computer simulations has been done, which shows perfect match
Focusing a deterministic single-ion beam
We focus down an ion beam consisting of single 40Ca+ ions to a spot size of a
few mum using an einzel-lens. Starting from a segmented linear Paul trap, we
have implemented a procedure which allows us to deterministically load a
predetermined number of ions by using the potential shaping capabilities of our
segmented ion trap. For single-ion loading, an efficiency of 96.7(7)% has been
achieved. These ions are then deterministically extracted out of the trap and
focused down to a 1sigma-spot radius of (4.6 \pm 1.3)mum at a distance of 257mm
from the trap center. Compared to former measurements without ion optics, the
einzel-lens is focusing down the single-ion beam by a factor of 12. Due to the
small beam divergence and narrow velocity distribution of our ion source,
chromatic and spherical aberration at the einzel-lens is vastly reduced,
presenting a promising starting point for focusing single ions on their way to
a substrate.Comment: 16 pages, 7 figure
Small-angle neutron scattering of D2O-C(12)E(5) mixtures and microemulsions with n-octane: Direct analysis by Fourier transformation
Nature of the Darwin term and contribution to the Lamb shift for an arbitrary spin of the nucleus
The contact Darwin term is demonstrated to be of the same origin as the
spin-orbit interaction. The correction to the Lamb shift,
generated by the Darwin term, is found for an arbitrary nonvanishing spin of
the nucleus, both half-integer and integer. There is also a contribution of the
same nature to the nuclear quadrupole moment.Comment: 9 pages, latex, no figure
Controlling the transport of an ion: Classical and quantum mechanical solutions
We investigate the performance of different control techniques for ion
transport in state-of-the-art segmented miniaturized ion traps. We employ
numerical optimization of classical trajectories and quantum wavepacket
propagation as well as analytical solutions derived from invariant based
inverse engineering and geometric optimal control. We find that accurate
shuttling can be performed with operation times below the trap oscillation
period. The maximum speed is limited by the maximum acceleration that can be
exerted on the ion. When using controls obtained from classical dynamics for
wavepacket propagation, wavepacket squeezing is the only quantum effect that
comes into play for a large range of trapping parameters. We show that this can
be corrected by a compensating force derived from invariant based inverse
engineering, without a significant increase in the operation time
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