The response of a molecular sheet with varying densities of simple, two-level system without lasing due to an ultra-short, wideband pulse centered at 2 eV is first investigated. The Fabry-Pérot modes rising from interference are observed, as well as the expected redshift in the transmission and reflection frequencies in the thin molecular sheet regime. Cautions regarding numerical instability and implementation of the Fast Fourier Transform are discussed. Upon activating the lasing levels of the molecules (creating a four-level system), the transmission and refection responses are measured for four combinations of molecular density and molecular sheet thickness. Lasing threshold and saturation phenomenon are observed and a clear lasing region is seen in the Power input/output analysis.
Population inversion is driving force that triggers lasing through stimulated emission. To investigate this, the populations of each of the four molecular energies levels are tracked for the same combinations of parameters in the previous tests. The population inversions and the threshold/saturation phenomena do not correspond to within reasonable limits. Inspection of the population data reveals a highly varied distribution within the molecular, suggesting that the system does not reach steady-state, and therefore and alternate method of analysis will need to be developed.
Having experimented with the simulations above, both the development of appropriate population analysis framework and the investigation of higher order dimensions (2-D and 3-D) will be pursed.
potential applications in various forms of computation i.e. optical and quantum, as well as
in energy engineering. Although this field has been under active research, there has been
little work done on describing the behaviors of threshold and saturation. Particularly, how
the gain-molecule behavior affects the lasing behavior has yet to be investigated.
In this work, the interaction of surface-plasmon-polaritons (SPPs) and molecules is
observed in lasing. Various phenomenologies are observed related to the appearance of the
threshold and saturation regions. The lasing profile, as a visual delimiter of lasing threshold
and saturation, is introduced and used to study various parametrical dependencies of lasing,
including the number-density of molecules, the molecular thickness and the frequency
detuning between the molecular transition frequency and the SPP resonant frequency. The
molecular population distributions are studied in terminal and dynamical methods and are
found to contain unexpected and theoretically challenging properties. Using an average
dynamical analysis, the simulated spontaneous emission cascade can be clearly seen.
Finally, theoretical derivations of simple 1D strands of dipoles are presented in both
the exact and mean-field approximation, within the density matrix formalism. Some
preliminary findings are presented, detailing the observed behaviors of some simple
systems.
In the quark model, meson states consisting of a quark/anti-quark pair must obey Poincaré symmetry. As a result of that symmetry, for meson total angular momentum J, parity P, and charge conjugation symmetry C, states with JPC= 0--, 0+-, 1-+, 2+-, 3-+, 4+-, … should not be observed. A meson observed experimentally with such quantum numbers would indicate a so-called “exotic” meson state. Exotic mesons can be multi-quark states like tetraquarks, a combination of two or more gluons known as glueballs, or a hybrid meson (qqg). Theories have suggested that three possible exotic meson states with the 1-+ quantum number: π1, η1, and η‘1,. However, no conclusive evidence for the existence of these three exotic states has been observed. This research will look for new states that decay to K* K final states with an emphasis on exotic mesons. An analysis of K+ K- π0 final states will be presented, where a restriction on the K - π0 invariant mass yields an unexpected enhancement in the K+ K- π0 spectrum.
Many of these results have been previously published in Physical Review B. The main results of Ch. 2 and Ch. 4 were packaged as “Enhanced vibrational electron energy-loss spectroscopy of adsorbate molecules” (99, 104110), and much of Ch. 5 appeared as “Prospects for detecting individual defect centers using spatially resolved electron energy loss spectroscopy” (100, 134103). The results from Ch. 3 are being prepared for a forthcoming article in the Journal of Chemical Physics.