112 research outputs found
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
Nonlinear Polariton Fluids in a Flatband Reveal Discrete Gap Solitons
Phase frustration in periodic lattices is responsible for the formation of
dispersionless flat bands. The absence of any kinetic energy scale makes flat
band physics critically sensitive to perturbations and interactions. We report
here on the experimental investigation of the nonlinear dynamics of cavity
polaritons in the gapped flat band of a one-dimensional Lieb lattice. We
observe the formation of gap solitons with quantized size and very abrupt
edges, signature of the frozen propagation of switching fronts. This type of
gap solitons belongs to the class of truncated Bloch waves, and had only been
observed in closed systems up to now. Here the driven-dissipative character of
the system gives rise to a complex multistability of the nonlinear domains
generated in the flat band. These results open up interesting perspective
regarding more complex 2D lattices and the generation of correlated photon
phases.Comment: 6 pages, 4 figures + supplemental material (6 pages, 6 figures
Engineering spin-orbit coupling for photons and polaritons in microstructures
One of the most fundamental properties of electromagnetism and special
relativity is the coupling between the spin of an electron and its orbital
motion. This is at the origin of the fine structure in atoms, the spin Hall
effect in semiconductors, and underlies many intriguing properties of
topological insulators, in particular their chiral edge states. Configurations
where neutral particles experience an effective spin-orbit coupling have been
recently proposed and realized using ultracold atoms and photons. Here we use
coupled micropillars etched out of a semiconductor microcavity to engineer a
spin-orbit Hamiltonian for photons and polaritons in a microstructure. The
coupling between the spin and orbital momentum arises from the polarisation
dependent confinement and tunnelling of photons between micropillars arranged
in the form of a hexagonal photonic molecule. Dramatic consequences of the
spin-orbit coupling are experimentally observed in these structures in the
wavefunction of polariton condensates, whose helical shape is directly visible
in the spatially resolved polarisation patterns of the emitted light. The
strong optical nonlinearity of polariton systems suggests exciting perspectives
for using quantum fluids of polaritons11 for quantum simulation of the
interplay between interactions and spin-orbit coupling.Comment: main text: pages 1-11 (4 figures); supplementary material: pages
12-28 (9 figures
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