11,424 research outputs found
The Development of Instruments for Assessment of Instructional Practices in Standards-Based Teaching
We provide a description and rationale for the development of two instruments: 1) a classroom observation protocol; and, 2) a teacher interview protocol—designed to document the impact of reform-based professional development with undergraduate mathematics and science faculty, and its impact on the resultant preparation of teachers. Constructed upon review of the research on teaching and standards documents in mathematics and science, these instruments form the basis for data collection in a three-year longitudinal study of teaching practice among early career teachers as well as undergraduate college faculty. In addition, we suggest further applications of the observation protocol beyond the original purpose of our research study
Atoms and Molecules in Cavities: From Weak to Strong Coupling in QED Chemistry
In this work, we provide an overview of how well-established concepts in the
fields of quantum chemistry and material sciences have to be adapted when the
quantum nature of light becomes important in correlated matter-photon problems.
Therefore, we analyze model systems in optical cavities, where the
matter-photon interaction is considered from the weak- to the strong coupling
limit and for individual photon modes as well as for the multi-mode case. We
identify fundamental changes in Born-Oppenheimer surfaces, spectroscopic
quantities, conical intersections and efficiency for quantum control. We
conclude by applying our novel recently developed quantum-electrodynamical
density-functional theory to single-photon emission and show how a
straightforward approximation accurately describes the correlated
electron-photon dynamics. This paves the road to describe matter-photon
interactions from first-principles and addresses the emergence of new states of
matter in chemistry and material science
Kohn-Sham Approach to Quantum Electrodynamical Density Functional Theory: Exact Time-Dependent Effective Potentials in Real Space
The density-functional approach to quantum electrodynamics is extending
traditional density-functional theory and opens the possibility to describe
electron-photon interactions in terms of effective Kohn-Sham potentials. In
this work, we numerically construct the exact electron-photon Kohn-Sham
potentials for a prototype system which consists of a trapped electron coupled
to a quantized electromagnetic mode in an optical high-Q cavity. While the
effective current that acts on the photons is known explicitly, the exact
effective potential that describes the forces exerted by the photons on the
electrons is obtained from a fixed-point inversion scheme. This procedure
allows us to uncover important beyond-mean-field features of the effective
potential which mark the breakdown of classical light-matter interactions. We
observe peak and step structures in the effective potentials, which can be
attributed solely to the quantum nature of light, i.e., they are real-space
signatures of the photons. Our findings show how the ubiquitous dipole
interaction with a classical electromagnetic field has to be modified in
real-space in order to take the quantum nature of the electromagnetic field
fully into account
A software development environment utilizing PAMELA
Hardware capability and efficiency has increased dramatically since the invention of the computer, while software programmer productivity and efficiency has remained at a relatively low level. A user-friendly, adaptable, integrated software development environment is needed to alleviate this problem. The environment should be designed around the Ada language and a design methodology which takes advantage of the features of the Ada language as the Process Abstraction Method for Embedded Large Applications (PAMELA)
Cavity Born-Oppenheimer Approximation for Correlated Electron-Nuclear-Photon Systems
In this work, we illustrate the recently introduced concept of the cavity
Born-Oppenheimer approximation for correlated electron-nuclear-photon problems
in detail. We demonstrate how an expansion in terms of conditional electronic
and photon-nuclear wave functions accurately describes eigenstates of strongly
correlated light-matter systems. For a GaAs quantum ring model in resonance
with a photon mode we highlight how the ground-state electronic
potential-energy surface changes the usual harmonic potential of the free
photon mode to a dressed mode with a double-well structure. This change is
accompanied by a splitting of the electronic ground-state density. For a model
where the photon mode is in resonance with a vibrational transition, we observe
in the excited-state electronic potential-energy surface a splitting from a
single minimum to a double minimum. Furthermore, for a time-dependent setup, we
show how the dynamics in correlated light-matter systems can be understood in
terms of population transfer between potential energy surfaces. This work at
the interface of quantum chemistry and quantum optics paves the way for the
full ab-initio description of matter-photon systems
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