61,776 research outputs found
Reply on `comment on our paper `Single two-level ion in an anharmonic-oscillator trap: Time evolution of the Q function and population inversion ''
We show here that the model Hamiltonian used in our paper for ion vibrating
in a q-analog harmonic oscillator trap and interacting with a classical
single-mode light field is indeed obtained by replacing the usual bosonic
creation and annihilation operators of the harmonic trap model by their
q-deformed counterparts. The approximations made in our paper amount to using
for the ion-laser interaction in a q-analog harmonic oscillator trap, the
operator F_{q}=exp{-(|\epsilon|^2}/2)}exp{i\epsilon A^{\dagger}}exp{i\epsilon
A}, which is analogous to the corresponding operator for ion in a harmonic
oscillator trap that is . In our article we do not claim to have diagonalized the
operator, , for which the basis states
|g,m> and |e,m> are not analytic vectors.Comment: Revtex, 4pages. To be Published in Physical Review A59, NO.4(April
99
Energy-irrigation nexus in South Asia: Improving groundwater conservation and power sector viability
Tube wells / Energy consumption / Costs / Electricity supplies / Groundwater irrigation / Water policy / Pumps / Water rates
Elastic response of filamentous networks with compliant crosslinks
Experiments have shown that elasticity of disordered filamentous networks
with compliant crosslinks is very different from networks with rigid
crosslinks. Here, we model and analyze filamentous networks as a collection of
randomly oriented rigid filaments connected to each other by flexible
crosslinks that are modeled as worm-like chains. For relatively large
extensions we allow for enthalpic stretching of crosslinks' backbones. We show
that for sufficiently high crosslink density, the network linear elastic
response is affine on the scale of the filaments' length. The nonlinear regime
can become highly nonaffine and is characterized by a divergence of the elastic
modulus at finite strain. In contrast to the prior predictions, we do not find
an asymptotic regime in which the differential elastic modulus scales linearly
with the stress, although an approximate linear dependence can be seen in a
transition from entropic to enthalpic regimes. We discuss our results in light
of the recent experiments.Comment: 10 pages, 11 figure
Schr\"{o}dinger cat state of trapped ions in harmonic and anharmonic oscillator traps
We examine the time evolution of a two level ion interacting with a light
field in harmonic oscillator trap and in a trap with anharmonicities. The
anharmonicities of the trap are quantified in terms of the deformation
parameter characterizing the q-analog of the harmonic oscillator trap.
Initially the ion is prepared in a Schr\"{o}dinger cat state. The entanglement
of the center of mass motional states and the internal degrees of freedom of
the ion results in characteristic collapse and revival pattern. We calculate
numerically the population inversion I(t), quasi-probabilities and
partial mutual quantum entropy S(P), for the system as a function of time.
Interestingly, small deformations of the trap enhance the contrast between
population inversion collapse and revival peaks as compared to the zero
deformation case. For \beta =3 and determines the average number
of trap quanta linked to center of mass motion) the best collapse and revival
sequence is obtained for \tau =0.0047 and \tau =0.004 respectively. For large
values of \tau decoherence sets in accompanied by loss of amplitude of
population inversion and for \tau \sim 0.1 the collapse and revival phenomenon
disappear. Each collapse or revival of population inversion is characterized by
a peak in S(P) versus t plot. During the transition from collapse to revival
and vice-versa we have minimum mutual entropy value that is S(P)=0. Successive
revival peaks show a lowering of the local maximum point indicating a
dissipative irreversible change in the ionic state. Improved definition of
collapse and revival pattern as the anharminicity of the trapping potential
increases is also reflected in the Quasi- probability versus t plots.Comment: Revised version, 16 pages,6 figures. Revte
Influence of substrate types and reflector proximities over a NDTC antenna
The influence of dissimilar substrates and reflector proximities over a newly developed Non-uniformly Distributed-Turns Coil (NDTC) antenna for High-Frequency (HF) Radio Frequency IDentification (RFID) applications is presented. In the study, the performance of the HF-RFID NDTC antenna over various substrates with deposited conductor thicknesses is conducted. In addition, the effect over a conceivably encountered reflector in the proximity of the antenna is considered. Insensitive reflection coefficient (S11) responses for different substrate permittivities were experienced and the diverse conductor types and thicknesses contributed to a compromised magnetic-field (H-field) and recalculated matching network. The matching network additionally preserves resonance when the antennas is in close proximity to the reflector and a predictable H-field response for the separation range is shown
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