222 research outputs found
Spontaneous rotating vortex rings in a parametrically driven polariton fluid
We present the theoretical prediction of spontaneous rotating vortex rings in
a parametrically driven quantum fluid of polaritons -- coherent superpositions
of coupled quantum well excitons and microcavity photons. These rings arise not
only in the absence of any rotating drive, but also in the absence of a
trapping potential, in a model known to map quantitatively to experiments. We
begin by proposing a novel parametric pumping scheme for polaritons, with
circular symmetry and radial currents, and characterize the resulting
nonequilibrium condensate. We show that the system is unstable to spontaneous
breaking of circular symmetry via a modulational instability, following which a
vortex ring with large net angular momentum emerges, rotating in one of two
topologically distinct states. Such rings are robust and carry distinctive
experimental signatures, and so they could find applications in the new
generation of polaritonic devices.Comment: 6 pages, 4 figure
Exciting polaritons with quantum light
We discuss the excitation of polaritons---strongly-coupled states of light
and matter---by quantum light, instead of the usual laser or thermal
excitation. As one illustration of the new horizons thus opened, we introduce
Mollow spectroscopy, a theoretical concept for a spectroscopic technique that
consists in scanning the output of resonance fluorescence onto an optical
target, from which weak nonlinearities can be read with high precision even in
strongly dissipative environments.Comment: 5 pages, 3 figure
Linear and nonlinear coupling of quantum dots in microcavities
We discuss the topical and fundamental problem of strong-coupling between a
quantum dot an the single mode of a microcavity. We report seminal quantitative
descriptions of experimental data, both in the linear and in the nonlinear
regimes, based on a theoretical model that includes pumping and quantum
statistics.Comment: Proceedings of the symposium Nanostructures: Physics and Technology
2010 (http://www.ioffe.ru/NANO2010), 2 pages in proceedings styl
Observation of long-lived polariton states in semiconductor microcavities across the parametric threshold
The excitation spectrum around the pump-only stationary state of a polariton
optical parametric oscillator (OPO) in semiconductor microcavities is
investigated by time-resolved photoluminescence. The response to a weak pulsed
perturbation in the vicinity of the idler mode is directly related to the
lifetime of the elementary excitations. A dramatic increase of the lifetime is
observed for a pump intensity approaching and exceeding the OPO threshold. The
observations can be explained in terms of a critical slowing down of the
dynamics upon approaching the threshold and the following onset of the soft
Goldstone mode
An acoustic black hole in a stationary hydrodynamic flow of microcavity polaritons
We report an experimental study of superfluid hydrodynamic effects in a
one-dimensional polariton fluid flowing along a laterally patterned
semiconductor microcavity and hitting a micron-sized engineered defect. At high
excitation power, superfluid propagation effects are observed in the polariton
dynamics, in particular, a sharp acoustic horizon is formed at the defect
position, separating regions of sub- and super-sonic flow. Our experimental
findings are quantitatively reproduced by theoretical calculations based on a
generalized Gross-Pitaevskii equation. Promising perspectives to observe
Hawking radiation via photon correlation measurements are illustrated.Comment: 5 pages Main + 5 pages Supplementary, 8 figure
Dynamics of formation and decay of coherence in a polariton condensate
We study the dynamics of formation and decay of a condensate of microcavity
polaritons. We investigate the relationship between the number of particles,
the emission's linewidth and its degree of linear polarization which serves as
the order parameter. Tracking the condensate's formation, we show that, even
when interactions are negligible, coherence is not determined only by
occupation of the ground state. As a result of the competition between the
coherent and thermal fractions of the condensate, the highest coherence is
obtained some time after the particle number has reached its maximum
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