Search results for "RAMAN"
showing 10 items of 1328 documents
Electronic and acoustic-phonon inter-Landau-level Raman scattering in GaAs/AlxGa1−xAs multiple quantum wells
1995
We present an experimental study of inter-Landau-level excitations in undoped GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As multiple quantum wells in high magnetic fields by means of Raman scattering. The experiments were performed in Faraday backscattering geometry with the field along the growth axis, using circularly polarized light for resonant excitation of low-index magneto-optical transitions between Landau levels. We observe two types of peaks. One of them, present in both Stokes and anti-Stokes regions at a constant Raman shift, corresponds to the electron cyclotron energy. We attribute it to electronic Raman scattering from a quasistationa…
Zeno-like phenomena in STIRAP processes
2011
The presence of a continuous measurement quantum Zeno effect in a stimulated Raman adiabatic passage is studied, exploring in detail a sort of self-competition of the damping, which drives the system toward a loss of population and, at the same time, realizes the conditions for optimizing the adiabatic passage.
Strong Exciton-Coherent Phonon Coupling in Single-Layer MoS2
2020
Broadband transient absorption with sub-20fs temporal resolution, supported by ab-initio calculations, quantitatively provides the strength of exciton-coherent phonon coupling in 1L-MoS2, showing a resonant profile around the C exciton.
Elastic light scattering from semiconductor structures: Localized versus propagating intermediate electronic excitations
1995
We present a theoretical study of the relative role of localized and propagating intermediate electronic states in the processes of elastic scattering of light. Only localized excitations lead to isotropic scattering in lowest-order perturbation theory. Inhomogeneous broadening of the optical transition affects the scattering efficiency from the ordered and disordered array of localized states in a qualitatively different way. The propagating electronic excitations may only contribute to elastic light scattering via higher-order processes. The scattering of excitons by impurities or the interface roughness potential is suggested as a mechanism for the contribution of propagating excitations…
State-selective chirped adiabatic passage on dynamically laser-aligned molecules
2005
We show that rovibrational state selectivity can be achieved by chirped adiabatic passage of molecules that are adiabatically aligned by a nonresonant laser field. We develop the tools to design the appropriate frequency and amplitude modulations that allow us to select a given route in the Hilbert space that leads to a final complete excitation of the chosen state, by infrared or by Raman processes. This method allows us to select a given vibrational state in a well-defined rotational $J$ state.
Arbitrary qudit gates by adiabatic passage
2013
We derive an adiabatic technique that implements the most general SU($d$) transformation in a quantum system of $d$ degenerate states, featuring a qudit. This technique is based on the factorization of the SU($d$) transformation into $d$ generalized quantum Householder reflections, each of which is implemented by a two-shot stimulated Raman adiabatic passage with appropriate static phases. The energy of the lasers needed to synthesize a single Householder reflection is shown to be remarkably constant as a function of $d$. This technique is directly applicable to a linear trapped ion system with $d+1$ ions. We implement the quantum Fourier transform numerically in a qudit with $d=4$ (defined…
Spatiotemporal Complexity in Step-Index Multimode Fibers
2016
We study supercontinuum generation in step-index fibers with a varying number of modes. We observe new spatiotemporal effects, including evidence of multimode spectral incoherent solitons, and a universal transition to spatiotemporal complexity.
Preliminary analysis of the pentad of 13CH4 from Raman and infrared spectra
1991
Abstract Preliminary results on the simultaneous analysis of infrared and Raman data of 13 CH 4 in the 3-μm region ( ν 1 , ν 3 , 2 ν 2 , ν 2 + ν 4 , and 2 ν 4 ) are presented. The infrared spectrum of 13 CH 4 (90% enriched) has been recorded with the Fourier transform spectrometer at Kitt Peak National Observatory. Line positions have been measured with a relative accuracy of 0.0001 cm −1 (for well-isolated lines) using 0.0118-cm −1 resolution spectra. In order to compensate for the lack of infrared information about low J transitions of vibrational bands forbidden in infrared, two spectra of the ν 1 ( A 1 ) and 2 ν 2 ( A 1 ) Q branches have been recorded in Dijon by inverse Raman spectrosc…
Study of the Fundamental Bands of 70GeD4 by High-Resolution Raman and Infrared Spectroscopy: First Experimental Determination of the Equilibrium Bond…
2002
Abstract The four fundamental bands of 70 GeD 4 have been analyzed using the STDS software developed in Dijon (http://www.u-bourgogne.fr/LPUB/sTDS.html). Both infrared and Raman spectra were used to observe all fundamental bands. Infrared spectra of monoisotopic 70 GeD 4 were recorded in the regions 600 and 1500 cm −1 using the Bruker 120HR interferometer at Wuppertal. The resolution (1/maximum optical path difference) was between 2.3 and 3.3×10 −3 cm −1 for the ν 3 and ν 4 infrared-active fundamental bands as well as for the interacting ν 2 band. A high-resolution stimulated Raman spectrum of the ν 1 band has been recorded in Madrid. The instrumental resolution of the Raman spectrum was 3.…
A Look at Some Remarkable Mathematical Techniques
1996
The nonlinear equations that we have encountered in the previous chapters can be solved by using mathematical techniques such as the powerful inverse scattering transform (IST) (Gardner et al. 1967) and the remarkable Hirota method (Hirota 1971). Specifically, in addition to the one-soliton solutions, explicit multisoliton solutions representing the interaction of any number of solitons can be constructed. Moreover, in several cases a precise prediction, closely related to experiments, can be made by the IST of the nonlinear response of the physical system, that is, of the number of solitons that can emerge from a finite initial disturbance (Zakharov, 1980. Ablowitz and Segur 1981; Calogero…