70 research outputs found
Book Reviews
Review of Prehistory, by Derek Roe; Aspects of Prehistory, by Grahame Clark; World Prehistory, by Grahame Clark; Introductory Readings in Archaeology, by Brian M. Fagan, ed.; The Origins of Civilization, by Carroll L. Riley; The Archaeology of Early Man, by J. M. Coles and E. S. Higgs; Shipwrecks and Archaeology, by Peter Throckmorton; A History of Dyed Textiles, by Stuart Robinson; Food in Antiquity, by Don and Patricia Brothwell; World Archaeology, Vol. 1, nos. 1, 2, 3, by Roy Hodson and Colin Platt, eds.; The Structure and Growth of Australia's Aboriginal Population, by F. Lancaster Jones; Attitudes and Social Conditions, by Ronald Taft, John L. M. Dawson, and Pamela Beasley; Aboriginal Settlements, by J. P. M. Long; The Destruction of Aboriginal Society, by C. D. Rowley; Aboriginal Advancement to Integration, by H. P. Schapper
Coupled Bose-Einstein condensate: Collapse for attractive interaction
We study the collapse in a coupled Bose-Einstein condensate of two types of
bosons 1 and 2 under the action of a trap using the time-dependent
Gross-Pitaevskii equation. The system may undergo collapse when one, two or
three of the scattering lengths for scattering of boson with ,
, are negative representing an attractive interaction. Depending
on the parameters of the problem a single or both components of the condensate
may experience collapse.Comment: 5 pages and 9 figures, small changes mad
Toward scalable quantum computation with cavity QED systems
We propose a scheme for quantum computing using high-Q cavities in which the
qubits are represented by single cavity modes restricted in the space spanned
by the two lowest Fock states. We show that single qubit operations and
universal multiple qubit gates can be implemented using atoms sequentially
crossing the cavities.Comment: 14 pages, 8 figure
Dynamics of evaporative cooling in magnetically trapped atomic hydrogen
We study the evaporative cooling of magnetically trapped atomic hydrogen on
the basis of the kinetic theory of a Bose gas. The dynamics of trapped atoms is
described by the coupled differential equations, considering both the
evaporation and dipolar spin relaxation processes. The numerical time-evolution
calculations quantitatively agree with the recent experiment of Bose-Einstein
condensation with atomic hydrogen. It is demonstrated that the balance between
evaporative cooling and heating due to dipolar relaxation limits the number of
condensates to 9x10^8 and the corresponding condensate fraction to a small
value of 4% as observed experimentally.Comment: 5 pages, REVTeX, 3 eps figures, Phys. Rev. A in pres
Simple method for excitation of a Bose-Einstein condensate
An appropriate, time-dependent modification of the trapping potential may be
sufficient to create effectively collective excitations in a cold atom
Bose-Einstein condensate. The proposed method is complementary to earlier
suggestions and should allow the creation of both dark solitons and vortices.Comment: 8 pages, 7 figures, version accepted for publication in Phys. Rev.
Split-merge cycle, fragmented collapse, and vortex disintegration in rotating Bose-Einstein condensates with attractive interactions
The dynamical instabilities and ensuing dynamics of singly- and
doubly-quantized vortex states of Bose-Einstein condensates with attractive
interactions are investigated using full 3D numerical simulations of the
Gross-Pitaevskii equation. With increasing the strength of attractive
interactions, a series of dynamical instabilities such as quadrupole, dipole,
octupole, and monopole instabilities emerge. The most prominent instability
depends on the strength of interactions, the geometry of the trapping
potential, and deviations from the axisymmetry due to external perturbations.
Singly-quantized vortices split into two clusters and subsequently undergo
split-merge cycles in a pancake-shaped trap, whereas the split fragments
immediately collapse in a spherical trap. Doubly-quantized vortices are always
unstable to disintegration of the vortex core. If we suddenly change the
strength of interaction to within a certain range, the vortex splits into three
clusters, and one of the clusters collapses after a few split-merge cycles. The
vortex split can be observed using a current experimental setup of the MIT
group.Comment: 11 pages, 10 figure
Generation of entangled states of two atoms inside a leaky cavity
An in-depth theoretical study is carried out to examine the
quasi-deterministic entanglement of two atoms inside a leaky cavity. Two
-type three-level atoms, initially in their ground states, may become
maximally entangled through the interaction with a single photon. By working
out an exact analytic solution, we show that the probability of success depends
crucially on the spectral function of the injected photon. With a cavity
photon, one can generate a maximally entangled state with a certain probability
that is always less than 50%. However, for an injected photon with a narrower
spectral width, this probability can be significantly increased. In particular,
we discover situations in which entanglement can be achieved in a single trial
with an almost unit probability
A developmental analysis of communication between mothers and infants with Down's syndrome
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68850/2/10.1177_027112148300300110.pd
Many particle entanglement in two-component Bose-Einstein Condensates
We investigate schemes to dynamically create many particle entangled states
of a two component Bose-Einstein condensate in a very short time proportional
to 1/N where is the number of condensate particles. For small we
compare exact numerical calculations with analytical semiclassical estimates
and find very good agreement for . We also estimate the effect of
decoherence on our scheme, study possible scenarios for measuring the entangled
states, and investigate experimental imperfections.Comment: 12 pages, 8 figure
Three-body halos. V. Computations of continuum spectra for Borromean nuclei
We solve the coordinate space Faddeev equations in the continuum. We employ
hyperspherical coordinates and provide analytical expressions allowing easy
computation of the effective potentials at distances much larger than the
ranges of the interactions where only s-waves in the different Jacobi
coordinates couple. Realistic computations are carried out for the Borromean
halo nuclei 6He (n+n+\alpha) for J\pi = 0+-, 1+-, 2+- and 11Li (n+n+9Li) for
(1/2)+-, (3/2)+-, (5/2)+-. Ground state properties, strength functions, Coulomb
dissociation cross sections, phase shifts, complex S-matrix poles are computed
and compared to available experimental data. We find enhancements of the
strength functions at low energies and a number of low-lying S-matrix poles.Comment: 35 pages, 14 figure
- …