Séminaire du LPTMS: P. Soulé et P.-E. Larré


11:00 - 12:00

LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay
15 Rue Georges Clemenceau, Orsay, 91405
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Wave pattern generated by an obstacle moving in a one-dimensional polariton condensate

Pierre-Elie Larré, LPTMS

Motivated by recent experiments on generation of wave patterns in polariton condensates, we analyze superfluid and dissipative characteristics of the one-dimensional flow of a nonresonantly-pumped polariton condensate past a localized obstacle. We consider the response of the condensate flow in the weak-perturbation limit, but also by means of the Whitham averaging theory in the nonlinear regime. One of the results of this work is the identification of a new time-dependent regime separating two types of stationary flows (a mostly viscous one and another one dominated by Cherenkov radiation).

I will also present results obtained by including polarization effects in the description of the polariton condensate, and I will argue that similar effects in presence of an acoustic horizon offer possibilities for demonstrating Hawking-like radiation in polariton condensates.

Many-body study of a quantum point contact in the fractional quantum Hall regime

Paul Soulé, LPTMS

Fractional Quantum Hall (FQH) fluids have a low-energy effective theory localized at their edges. The edge states are expected to form a very special one-dimensional strongly interacting electronic system, a chiral Luttinger liquid. Depending on FQH phases, a variety of 1D models has been proposed. But only poor experimental agreements have been found yet.
Using exact diagonalizations in the cylinder geometry we identify the edge modes in the presence of a parabolic confining potential at Landau level filling factors v=1/3 and v=5/2. If we change the sign of the potential we can access both the tunneling through the bulk of the fluid and the tunneling between spatially separated droplets, and measure numerically Luttinger parameters in both cases. These phenomena are at the basis of tunneling experiments in quantum point contact devices of two-dimensional electron gases.

P. Soulé, T. Jolicoeur, Phys. Rev. B 86, 115214 (2012)
P. Soulé, T. Jolicoeur, in preparation

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