10 research outputs found
Polarization dependence of semiconductor exciton and biexciton contributions to phase-resolved optical two-dimensional Fourier-transform spectra
We study the coherent light-matter interactions of GaAs quantum wells
associated with excitons, biexcitons and many-body effects. For most
polarization configurations, excitonic features dominate the phase-resolved
two-dimensional Fourier-transform (2DFT) spectra and have dispersive
lineshapes, indicating the presence of many-body interactions. For cross-linear
excitation, excitonic features become weak and absorptive due to the strong
suppression of many-body effects; a result that can not be directly determined
in transient four-wave mixing experiments. The biexcitonic features do not
weaken for cross-polarized excitation and thus are more important.Comment: 4 page, 3 figures, journal article - rapid communicatio
Two-dimensional double-quantum spectra reveal collective resonances in an atomic vapor
We report the observation of double-quantum coherence signals in a gas of
potassium atoms at twice the frequency of the one-quantum coherences. Since a
single atom does not have a state at the corresponding energy, this observation
must be attributed to a collective resonance involving multiple atoms. These
resonances are induced by weak inter-atomic dipole-dipole interactions, which
means that the atoms cannot be treated in isolation, even at a low density of
cm
All-optical retrieval of the global phase for two-dimensional Fourier-transform spectroscopy
A combination of spatial interference patterns and spectral interferometry
are used to find the global phase for non-collinear two-dimensional
Fourier-transform (2DFT) spectra. Results are compared with those using the
spectrally resolved transient absorption (STRA) method to find the global phase
when excitation is with co-linear polarization. Additionally cross-linear
polarized 2DFT spectra are correctly phased using the all-optical technique,
where the SRTA is not applicable.Comment: 6 pages, 7 figures, journal publicatio
Coherent exciton-phonon coupling in perovskite semiconductor nanocrystals studied by two-dimensional electronic spectroscopy
Experimental Determination of the Rotational Constants of High-Lying Vibrational Levels of Ultracold Cs<sub>2</sub> in the 0<sub>g</sub><sup>–</sup> Purely Long-Range State
We
report on a quantitative experimental determination of the rotational
constants for the high-lying vibrational levels of the ultracold pure
long-range Cesium molecules formed via photoassociation. The scheme
relies on a precise reference of frequency difference in a double
photoassociation spectroscopy, which is induced by two laser beams
based on an acoustic-optical modulator. The rotational constants are
obtained by fitting a nonrigid rotor model into the frequency intervals
of the neighboring rotational levels deduced from the reference