15,607 research outputs found
Lasing with Topological Weyl Semimetal
Lasing behavior of optically active planar topological Weyl semimetal (TWS)
is investigated in view of the Kerr and Faraday rotations. Robust topological
character of TWS is revealed by the presence of Weyl nodes and relevant surface
conductivities. We focus our attention on the surfaces where no Fermi arcs are
formed, and thus Maxwell equations contain topological terms. We explicitly
demonstrate that two distinct lasing modes arise because of the presence of
effective refractive indices which lead to the birefringence phenomena.
Transfer matrix is constructed in such a way that reflection and transmission
amplitudes involve matrix-valued components describing the bimodal
character of the TWS laser. We provide associated parameters of the topological
laser system yielding the optimal impacts. We reveal that gain values
corresponding to the lasing threshold display a quantized behavior, which
occurs due to topological character of the system. Our proposal is supported by
the corresponding graphical demonstrations. Our observations and predictions
suggest a concrete way of forming TWS laser and coherent perfect absorber; and
are awaited to be confirmed by an experimental realization based on our
computations.Comment: 17 pages, 9 figures, 3 table
Interaction of bimodal fields with few-level atoms in cavities and traps
The spectacular experimental results of the last few years in cavity quantum
electrodynamics and trapped ions research has led to very high level laboratory
performances. Such a stimulating situation essentially stems from two decisive
advancements. The first is the invention of reliable protocols for the
manipulation of single atoms. The second is the ability to produce desired
bosonic environments on demand. These progresses have led to the possibility of
controlling the form of the coupling between individual atoms and an arbitrary
number of bosonic modes. As a consequence, fundamental matter-radiation
interaction models like, for instance, the JC model and most of its numerous
nonlinear multiphoton generalizations, have been realized or simulated in
laboratory and their dynamical features have been tested more or less in
detail. This topical paper reviews the state of the art of the theoretical
investigations and of the experimental observations concerning the dynamical
features of the coupling between single few-level atoms and two bosonic modes.
In the course of the paper we show that such a configuration provides an
excellent platform for investigating various quantum intermode correlation
effects tested or testable in the cavity quantum electrodynamics and trapped
ion experimental realms. In particular we discuss a mode-mode correlation
effect appearing in the dynamics of a two-level atom quadratically coupled to
two bosonic modes. This effect, named parity effect, consists in a high
sensitivity to the evenness or oddness of the total number of bosonic
excitations.Comment: Topical Review. To appear on J. Mod. Op
Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 314)
This bibliography lists 139 reports, articles, and other documents introduced into the NASA scientific and technical information system in August, 1988
Dynamic Transition in the Structure of an Energetic Crystal during Chemical Reactions at Shock Front Prior to Detonation
Mechanical stimuli in energetic materials initiate chemical reactions at shock fronts prior to detonation. Shock sensitivity measurements provide widely varying results, and quantum-mechanical calculations are unable to handle systems large enough to describe shock structure. Recent developments in reactive force-field molecular dynamics (ReaxFF-MD) combined with advances in parallel computing have paved the way to accurately simulate reaction pathways along with the structure of shock fronts. Our multimillion-atom ReaxFF-MD simulations of l,3,5-trinitro-l,3,5-triazine (RDX) reveal that detonation is preceded by a transition from a diffuse shock front with well-ordered molecular dipoles behind it to a disordered dipole distribution behind a sharp front
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