118 research outputs found
Coherent population trapping in two-electron three-level systems with aligned spins
The possibility of coherent population trapping in two electron states with
aligned spins (ortho-system) is evidenced. From the analysis of a three-level
atomic system containing two electrons, and driven by the two laser fields
needed for coherent population trapping, a conceptually new kind of
two-electron dark state appears. The properties of this trapping are studied
and are physically interpreted in terms of a dark hole, instead of a dark
two-electron state. This technique, among many other applications, offers the
possibility of measuring, with subnatural resolution, some superposition-state
matrix-elements of the electron-electron correlation that due to their time
dependent nature are inaccesible by standard measuring procedures.Comment: 10 pages and 4 figure
Bartlett pear unsaturated ethyl deconoates and C9 compounds among components characterizing cv. Catalan roxo grape marc distillates
Catalan roxo marc distillates contain compounds at an unusual level in a grape derivate. The most peculiar are several unsaturated ethyl decanoates typical of Bartlett pear distillates and derived from ethyl esters found in the grape skins, some of which partially modified in the stereoisomery probably by the fermentation process. Remarkable compounds are unbranched aliphatic C-9 compounds at different oxidation state as well as ethyl nonanoate. At sensorially interesting levels methyl and ethyl salicylate and ethyl cinnamate, monoterpenols typical of floral-like varieties, vitispiranes and 4-ethylguaiacol are detected. Methyl salicylate is found in the berry as free and bound compound as several monoterpenols
Steady state behaviour in atomic three-level lambda and ladder systems with incoherent population pumping
The steady state in three-level lambda and ladder systems is studied. It is
well-known that in a lambda system this steady state is the coherent population
trapping state, independent of the presence of spontaneous emission. In
contrast, the steady state in a ladder system is in general not stable against
radiative decay and exhibits a minimum in the population of the ground state.
It is shown that incoherent population pumping destroys the stability of the
coherent population trapping state in the lambda system and suppresses a
previously discovered sharp dip in the steady state response. In the ladder
system the observed minimum disappears in the presence of an incoherent pump on
the upper transition.Comment: 4 pages, RevTex, 5 figures, to appear in Phys. Rev.
Destabilization of dark states and optical spectroscopy in Zeeman-degenerate atomic systems
We present a general discussion of the techniques of destabilizing dark
states in laser-driven atoms with either a magnetic field or modulated laser
polarization. We show that the photon scattering rate is maximized at a
particular evolution rate of the dark state. We also find that the atomic
resonance curve is significantly broadened when the evolution rate is far from
this optimum value. These results are illustrated with detailed examples of
destabilizing dark states in some commonly-trapped ions and supported by
insights derived from numerical calculations and simple theoretical models.Comment: 14 pages, 10 figure
Adiabatic following criterion, estimation of the nonadiabatic excitation fraction and quantum jumps
An accurate theory describing adiabatic following of the dark, nonabsorbing
state in the three-level system is developed. An analytical solution for the
wave function of the particle experiencing Raman excitation is found as an
expansion in terms of the time varying nonadiabatic perturbation parameter. The
solution can be presented as a sum of adiabatic and nonadiabatic parts. Both
are estimated quantitatively. It is shown that the limiting value to which the
amplitude of the nonadiabatic part tends is equal to the Fourier component of
the nonadiabatic perturbation parameter taken at the Rabi frequency of the
Raman excitation. The time scale of the variation of both parts is found. While
the adiabatic part of the solution varies slowly and follows the change of the
nonadiabatic perturbation parameter, the nonadiabatic part appears almost
instantly, revealing a jumpwise transition between the dark and bright states.
This jump happens when the nonadiabatic perturbation parameter takes its
maximum value.Comment: 33 pages, 8 figures, submitted to PRA on 28 Oct. 200
Optimization systems developed to improve the yield on tungsten and tantalum extraction and reduce associated costs – the EU HORIZON 2020 Optimore project (grant no. 642201)
Peer ReviewedPostprint (published version
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