23,951 research outputs found
The Use of Dramatic Demonstrations to Enhance the Motivation and Learning of Chemistry Students
As part of the Virginia Collaborative for Excellence in the Preparation of Teachers (VCEPT) project, a series of demonstrations was incorporated into Chemistry 100: Man and Environment, a science course taken by non-science majors including many prospective K-12 teachers. Dramatic chemical demonstrations were ïŹrst presented to the undergraduate students by the instructor, and then they used demonstration activities to teach each other during the semester. Finally, these undergraduates presented to the K-6 students in the Norfolk Statue University (NSU) Summer Childrenâs College. The perceptions of science by the undergraduates at the beginning and end of the course were assessed using a questionnaire. The responses of the K-6 students in the Childrenâs College were assessed through informal interviews and audience response. The use of these demonstrations seemed to change the perception of science held by the undergraduate students. In addition, this limited assessment indicated that these demonstrations may have helped more of the undergraduates consider teaching as a career option
An equations-of-motion approach to quantum mechanics: application to a model phase transition
We present a generalized equations-of-motion method that efficiently
calculates energy spectra and matrix elements for algebraic models. The method
is applied to a 5-dimensional quartic oscillator that exhibits a quantum phase
transition between vibrational and rotational phases. For certain parameters,
10 by 10 matrices give better results than obtained by diagonalising 1000 by
1000 matrices.Comment: 4 pages, 1 figur
Scalable photonic quantum computation through cavity-assisted interaction
We propose a scheme for scalable photonic quantum computation based on cavity
assisted interaction between single-photon pulses. The prototypical quantum
controlled phase-flip gate between the single-photon pulses is achieved by
successively reflecting them from an optical cavity with a single-trapped atom.
Our proposed protocol is shown to be robust to practical nose and experimental
imperfections in current cavity-QED setups.Comment: 5 pages, 2 figure
Fast and robust two-qubit gates for scalable ion trap quantum computing
We propose a new concept for a two-qubit gate operating on a pair of trapped
ions based on laser coherent control techniques. The gate is insensitive to the
temperature of the ions, works also outside the Lamb-Dicke regime, requires no
individual addressing by lasers, and can be orders of magnitude faster than the
trap period
Classical mappings of the symplectic model and their application to the theory of large-amplitude collective motion
We study the algebra Sp(n,R) of the symplectic model, in particular for the
cases n=1,2,3, in a new way. Starting from the Poisson-bracket realization we
derive a set of partial differential equations for the generators as functions
of classical canonical variables. We obtain a solution to these equations that
represents the classical limit of a boson mapping of the algebra. The
relationship to the collective dynamics is formulated as a theorem that
associates the mapping with an exact solution of the time-dependent Hartree
approximation. This solution determines a decoupled classical symplectic
manifold, thus satisfying the criteria that define an exactly solvable model in
the theory of large amplitude collective motion. The models thus obtained also
provide a test of methods for constructing an approximately decoupled manifold
in fully realistic cases. We show that an algorithm developed in one of our
earlier works reproduces the main results of the theorem.Comment: 23 pages, LaTeX using REVTeX 3.
Quasi dynamical symmetry in an interacting boson model phase transition
The oft-observed persistence of symmetry properties in the face of strong
symmetry-breaking interactions is examined in the SO(5)-invariant interacting
boson model. This model exhibits a transition between two phases associated
with U(5) and O(6) symmetries, respectively, as the value of a control
parameter progresses from 0 to 1. The remarkable fact is that, for intermediate
values of the control parameter, the model states exhibit the characteristics
of its closest symmetry limit for all but a relatively narrow transition region
that becomes progressively narrower as the particle number of the model
increases. This phenomenon is explained in terms of quasi-dynamical symmetry.Comment: 4 figure
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