(b) Write out the equations for the time dependence of ρ11, ρ22, ρ12 and ρ21 assuming that a light field interaction V = -μ12Ee iωt + c.c. couples only levels |1> and |2>, and that the excited levels exhibit spontaneous decay. (8 marks) (c) Under steady-state conditions, find the ratio of populations in states |2> and |3>. (3 marks) (d) Find the slowly varying amplitude ̃ ρ 12 of the polarization ρ12 = ̃ ρ 12e iωt . (6 marks) (e) In the limiting case that no decay is possible from intermediate level |3>, what is the ground state population ρ11(∞)? (2 marks) 2. (15 marks total) In a 2-level atom system subjected to a strong field, dressed states are created in the form |D1(n)> = sin θ |1,n> + cos θ |2,n-1> |D2(n)> = cos θ |1,n> sin θ |2,n-1>

The Quantum Theory of Light

Random-matrix theories in quantum physics : common concepts

We review the development of random-matrix theory (RMT) during the last decade. We emphasize both the theoretical aspects, and the application of the theory to a number of fields. These comprise chaotic and disordered systems, the localization problem, many-body quantum systems, the Calogero-Sutherland model, chiral symmetry breaking in QCD, and quantum gravity in two dimensions. The review is preceded by a brief historical survey of the developments of RMT and of localization theory since their inception. We emphasize the concepts common to the above-mentioned fields as well as the great diversity of RMT. In view of the universality of RMT, we suggest that the current development signals the emergence of a new "statistical mechanics": Stochasticity and general symmetry requirements lead to universal laws not based on dynamical principles.

Random Matrix Theories in Quantum Physics: Common Concepts

In this review article a comprehensive analysis of the developments in ultraviolet (UV) detector technology is described. At the beginning, the classification of UV detectors and general requirements imposed on these detectors are presented. Further considerations are restricted to modern semiconductor UV detectors, so the basic theory of photoconductive and photovoltaic detectors is presented in a uniform way convenient for various detector materials. Next, the current state of the art of different types of semiconductor UV detectors is presented. Hitherto, the semiconductor UV detectors have been mainly fabricated using Si. Industries such as the aerospace, automotive, petroleum, and others have continuously provided the impetus pushing the development of fringe technologies which are tolerant of increasingly high temperatures and hostile environments. As a result, the main efforts are currently directed to a new generation of UV detectors fabricated from wide band‐gap semiconductors the most promising ...

Semiconductor ultraviolet detectors

Intramolecular vibrational redistribution is a fundamental phenomenon observed in polyatomic molecules when sufficiently excited vibrationally. In this paper, results mostly from the last two decades of research on this subject are summarized, obtained either from infrared spectroscopy with a resolution of as high as cm or, in a different approach, by using various pump-probe schemes with a temporal resolution from dozens of picoseconds to subpicoseconds.

https://iopscience.iop.org/article/10.3367/UFNe.0182.201210e.1047/pdf

Intramolecular vibrational redistribution: from high-resolution spectra to real-time dynamics

We show that the Fourier transform of very complex spectra gives a sound measurement of long-range statistical properties of levels even in cases of badly resolved, poorly correlated spectra. Examples of nuclear energy levels, highly excited acetylene vibrational levels, and singlet-triplet anticrossing spectra in methylglyoxal are displayed.

/pdf/fourier-transform-a-tool-to-measure-statistical-level-2imdehy0bl.pdf

Fourier transform: A tool to measure statistical level properties in very complex spectra.

A recently proposed technique based on the Fourier transform of the spectrum is applied to the stimulated-emission pumping spectrum of acetylene at --26 500 cm/sup -1/ above the vibrational ground state. Correlations on two different time scales (--3 and --45 ps) were found from analysis of low-resolution (0.3 cm/sup -1/) and high-resolution (0.05 cm/sup -1/) spectra, respectively. Additional structure produced dynamic information on a wider (0.5--300 ps) time scale. The results show that acetylene at 26 500 cm/sup -1/ is in the transition from the regular to the chaotic regime.

Chaos and dynamics on 0.5-300 ps time scales in vibrationally excited acetylene: Fourier transform of stimulated-emission pumping spectrum.

A detailed analytical calculation of the photoelectric quantum yield in Schottky diodes is presented. The transport of carriers in the surface space charge region is treated explicitly, taking account of photogeneration, diffusion and drift in the non-uniform electric field. Boundary conditions at the interface are expressed in terms of surface recombination velocity and emission velocity of excess carriers into the metal. It is shown that the metal-semiconductor interface strongly affects the collection efficiency of short wavelength generated electron-hole pairs. This effect basically originates in the emission flux of majority carriers into the metal. Current, charge carriers distributions and quantum yields are computed using the data of AuCdTe Schottky barriers.

Theoretical analysis of the quantum photoelectric yield in schottky diodes

A symmetry breaking of the ungerade-gerade character through hyperfine perturbation has been directly observed for the first time in a homonuclear diatomic molecule ($^{127}\mathrm{I}_{2}$). An important consequence of this symmetry breaking is the mixing of ortho and para modifications. Evidenced by anomalies in the observed hfs of high-lying rovibrational levels in the $B{{0}_{\mathrm{u}}}^{+}$ state and extra lines, it is due to a hyperfine perturbation of this state by a 1g state sharing the same dissociation limit. Such a situation should be met in other molecules.

Hyperfine-Induced Ungerade-Gerade Symmetry Breaking in a Homonuclear Diatomic Molecule near a Dissociation Limit: 127 I 2 at the 2 P 32 - 2 P 12 Limit

The vibrational spectrumof acetylene is reported. This is the stimulat emission pumping spectrum obtained by stimulated downward transition from an upper electronic state to the ground electronic surface.Broad band and high resolution spectra were recorded at 25840−27250 wave numbers.(AIP)

Jean-Paul Pique

Papers

Fourier transform: A tool to measure statistical level properties in very complex spectra.

Chaos and dynamics on 0.5-300 ps time scales in vibrationally excited acetylene: Fourier transform of stimulated-emission pumping spectrum.

Theoretical analysis of the quantum photoelectric yield in schottky diodes

Hyperfine-Induced Ungerade-Gerade Symmetry Breaking in a Homonuclear Diatomic Molecule near a Dissociation Limit: 127 I 2 at the 2 P 32 - 2 P 12 Limit

Broad spectral features in the stimulated emission pumping spectrum of acetylene