Search results for "harmonic"
showing 10 items of 984 documents
Phonon-to-spin mapping in a system of a trapped ion via optimal control
2015
We propose a protocol for measurement of the phonon number distribution of a harmonic oscillator based on selective mapping to a discrete spin-1/2 degree of freedom. We consider a system of a harmonically trapped ion, where a transition between two long-lived states can be driven with resolved motional sidebands. The required unitary transforms are generated by amplitude-modulated polychromatic radiation fields, where the time-domain ramps are obtained from numerical optimization by application of the chopped random basis algorithm (CRAB). We provide a detailed analysis of the scaling behavior of the attainable fidelities and required times for the mapping transform with respect to the size…
Study of Mode Competition in the Third Harmonic Gyrotron with Inclusion of the Electron Velocity Spread and the Beam Width
2018
Influence of the electron velocity spread and the beam width on the mode competition and efficiency is investigated in the 1.185- THz third harmonic gyrotron to be used in dynamical nuclear polarization - nuclear magnetic resonance (DNP-NMR) spectrometer.
Three-body forces in the quark model
2008
The constituent quark model has been very useful for the description of many physical properties of baryons, achieving in most cases a fair agreement with the experimental data 1 The model is based on a non relativistic QCD-inspired dynamics including a harmonic oscillator (h.o.) confinement potential and a spin dependent (hyperfine) interaction. The use of Lovelace coordinates p, ~ avoides any problem with the center of mass motion, while the h.o. potential provides a simple basis for ana ly t ica l calculations, which is a very important feature for many applications, like the evaluation of form factors and Meson Exchange Currents 2. On the other hand the h.o. spectrum is too degenerate w…
Plasma emission at the laser tripled frequency
2003
The third harmonic generation in the skin-layer of a dense hot plasma due to inverse bremsstrahlung is investigated for regimes having increasing experimental relevance. New analytical dependencies of the radiation flux density at the frequency 3ω on the plasma and fundamental wave parameters are established.
The empirical equilibrium structure of diacetylene
2008
High-level quantum-chemical calculations are reported at the MP2 and CCSD(T) levels of theory for the equilibrium structure and the harmonic and anharmonic force fields of diacetylene, HCCCCH. The calculations were performed employing Dunning's hierarchy of correlation-consistent basis sets cc-pVXZ, cc-pCVXZ, and cc-pwCVXZ, as well as the ANO2 basis set of Almloef and Taylor. An empirical equilibrium structure based on experimental rotational constants for thirteen isotopic species of diacetylene and computed zero-point vibrational corrections is determined (r_e^emp: rC-H=1.0615 A, rCtripleC=1.2085 A, rC-C = 1.3727 A) and in good agreement with the best theoretical structure (CCSD(T)/cc-pCV…
Principles of Ion Traps
2008
Three-dimensional confinement of charged particles requires a potential energy minimum at some point in space in order that the corresponding force is directed toward that point in all three dimensions. In general, the dependence of the magnitude of this force on the coordinates can have an arbitrary form; however, it is convenient to have a binding force that is harmonic, since this simplifies the analytical description of the particle motion. Thus, we assume
Coriolis interaction parameters of the (2100; F2) bands of SiH4 and GeH4. A test of local mode models
1995
Abstract The high-resolution spectra of the (2100; F 2 , N ), N = 1 and 2, bands of SiH 4 and GeH 4 have been recorded and preliminary analyzed. The Coriolis interaction parameter 2 Bζ 3 is obtained; it provides a test of three widely used models: the harmonically coupled anharmonic oscillators model with two different kinds of variables, and the normal mode model with Darling-Dennison resonance included.
Analysis of the transition from normal modes to local modes in a system of two harmonically coupled Morse oscillators
1992
The system consisting of two Morse oscillators coupled via either a potential or a kinetic quadratic term is considered. The corresponding classical equations of motion have been numerically integrated and the initial conditions have been systematically analyzed in the regime of low total excitation energy of the system. Particular attention was paid to the full characterization of an intermediate type of motion, herein called transition mode, which appears at total energy values in between those typical of normal modes and those where local and normal modes coexist. A previously proposed perturbative approach (Jaffe C, Brumer P (1980) J Chem Phys 73:5646) is reanalyzed and compared with th…
Measurement of optical second-harmonic generation from an individual single-walled carbon nanotube
2013
We show that optical second-harmonic generation (SHG) can be observed from individual single-walled carbon nanotubes (SWCNTs) and, furthermore, allows imaging of individual tubes. Detailed analysis of our results suggests that the structural noncentrosymmetry, as required for SHG, arises from the non-zero chiral angle of the SWCNT. SHG thus has potential as a fast, non-destructive, and simple method for imaging of individual nanomolecules and for probing their chiral properties. Even more, it opens the possibility to optically determine the handedness of individual SWCNTs.
Frenkel-Kontorova model with anharmonic interactions
1986
It is shown that consideration of more realistic interatomic potentials (with limited tensile strength) within the framework of the Frenkel-Kontorova model may lead to a breakdown of the soliton picture in systems with competing periodicities. Closed analytical expressions for the form of a single soliton in an anharmonic chain reveal discontinuities which indicate a disintegration of the entire system beyond some critical values of the misfit, and/or of the height of the periodic substrate potential. The length of anharmonic solitons depends essentially on both the sign and the magnitude of the misfit. The influence of misfit on the pinning-unpinning transition is also investigated.