905 research outputs found
Light dressed-excitons in an incoherent-electron sea: Evidence for Mollow-triplet and Autler-Townes doublet
We demonstrate that the interaction between excitons and a sea of incoherent
electrons does not preclude excitons dressing by light. We investigate the role
of exciton-electron scattering in the light dressing by measuring the dynamical
absorption spectrum of a modulation-doped CdTe quantum well, which shows a
clear evidence for significant electron scattering of the excitonic states. We
show the occurrence of dressed and correlated excitons by detecting quantum
coherent interferences through excitonic Autler-Townes doublet and ac Stark
splitting, which evolves to Mollow triplet with gain. We also evidence the
partial inhibition of the electron-exciton scattering by exciton-light
coupling
Notes històriques sobre Montblanc i Sarral (s. XIV-XVI)
Notes Històrique
Interacting many-body systems in quantum wells: Evidence for exciton-trion-electron correlations
We report on the nonlinear optical dynamical properties of excitonic
complexes in CdTe modulation-doped quantum wells, due to many-body interactions
among excitons, trions and electrons. These were studied by time and spectrally
resolved pump-probe experiments. The results reveal that the nonlinearities
induced by trions differ from those induced by excitons, and in addition they
are mutually correlated. We propose that the main source of these subtle
differences comes from the Pauli exclusion-principle through phase-space
filling and short-range fermion exchange.Comment: 5 pages, 4 figures. accepted for publications in Phys. Rev.
From single particle to superfuid excitations in a dissipative polariton gas
Using angle-resolved heterodyne four-wave-mixing technique, we probe the low
momentum excitation spectrum of a coherent polariton gas. The experimental
results are well captured by the Bogoliubov transformation which describes the
transition from single particle excitations of a normal fluid to
sound-wave-like excitations of a superfluid. In a dense coherent polariton gas,
we find all the characteristics of a Bogoliubov transformation, i.e. the
positive and negative energy branch with respect to the polariton gas energy at
rest, sound-wave-like shapes for the excitations dispersion, intensity and
linewidth ratio between the two branches in agreement with the theory. The
influence of the non-equilibrium character of the polariton gas is shown by a
careful analysis of its dispersion.Comment: 4 pages, 3 figure
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