1,498 research outputs found
Vortices in exciton-polariton condensates with polarization splitting
The presence of polarization splitting of exciton-polariton branches in
planar semiconductor microcavities has a pronounced effect on vortices in
polariton condensates. We show that the TE-TM splitting leads to the coupling
between the left and right half-vortices (vortices in the right and left
circular components of the condensate), that otherwise do not interact. We
analyze also the effect of linear polarization pinning resulted from a fixed
splitting between two perpendicular linear polarizations. In this case,
half-vortices acquire strings (solitons) attached to them. The half-vortices
with strings can be detected by observing the interference fringes of light
emitted from the cavity in two circular polarizations. The string affects the
fringes in both polarizations. Namely, the half-vortex is characterized by an
asymmetric fork-like dislocation in one circular polarization; the fringes in
the other circular polarization are continuous, but they are shifted by
crossing the string.Comment: 4 pages, 2 figs, Optics of Excitons in Confined Systems 11 (Madrid,
7-11 september 2009
Harvesting, coupling and control of single exciton coherences in photonic waveguide antennas
We perform coherent non-linear spectroscopy of individual excitons strongly
confined in single InAs quantum dots (QDs). The retrieval of their
intrinsically weak four-wave mixing (FWM) response is enabled by a
one-dimensional dielectric waveguide antenna. Compared to a similar QD embedded
in bulk media, the FWM detection sensitivity is enhanced by up to four orders
of magnitude, over a broad operation bandwidth. Three-beam FWM is employed to
investigate coherence and population dynamics within individual QD transitions.
We retrieve their homogenous dephasing in a presence of spectral wandering.
Two-dimensional FWM reveals off-resonant F\"orster coupling between a pair of
distinct QDs embedded in the antenna. We also detect a higher order QD
non-linearity (six-wave mixing) and use it to coherently control the FWM
transient. Waveguide antennas enable to conceive multi-color coherent
manipulation schemes of individual emitters.Comment: 7 pages, 8 Figure
Quantum correlations on quantum spaces
For given quantum (non-commutative) spaces and , we study the quantum space of maps , from to . In case of finite quantum spaces, these objects turn out to be behind a large class of maps which generalize the classical qc-correlations known from quantum information theory to the setting of quantum input and output sets. We prove various operator algebraic properties of the C* -algebras C() such as the lifting property and residual finite dimensionality. Inside C() we construct a universal operator system related to and , and show, among other things, that the embedding C() is hyperrigid and has another interesting property, which we call the strong extension property. Furthermore, C() is the C* -envelope of and a large class of non-signalling correlations on the quantum sets and arise from states on C() ⊗ C() as well as states on the commuting tensor product ⊗. Finally, we introduce and study the notion of a synchronous correlation with quantum input and output sets and prove several characterizations of such correlations and their relation to traces on C(
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