42 research outputs found
Analysis of Trapped Quantum Degenerate Dipolar Excitons
The dynamics of quantum degenerate two-dimensional dipolar excitons confined
in electrostatic traps is analyzed and compared to recent experiments. The
model results stress the importance of artificial trapping for achieving and
sustaining a quantum degenerate exciton fluid in such systems and suggest that
a long-lived, spatially uniform, and highly degenerate exciton system was
experimentally produced in those electrostatic traps.Comment: 4 pages 3 figure
Remote Dipolar Interactions for Objective Density Calibration and Flow Control of Excitonic Fluids
In this paper we suggest a method to observe remote interactions of spatially
separated dipolar quantum fluids, and in particular of dipolar excitons in GaAs
bilayer based devices. The method utilizes the static electric dipole moment of
trapped dipolar fluids to induce a local potential change on spatially
separated test dipoles. We show that such an interaction can be used for a
model- independent, objective fluid density measurements, an outstanding
problem in this field of research, as well as for inter-fluid exciton flow
control and trapping. For a demonstration of the effects on realistic devices,
we use a full two-dimensional hydrodynamical model
Nonlinear dynamics of a dense two-dimensional dipolar exciton gas
We use a simple model to describe the nonlinear dynamics of a dense two
dimensional dipolar exciton gas. The model predicts an initial fast expansion
due to dipole-dipole pressure, followed by a much slower diffusion. The model
is in very good agreement with recent experimental results. We show that the
dipole pressure induced expansion strongly constrains the time available for
achieving and observing Bose-Einstein quantum statistical effects, indicating a
need for spatial exciton traps. We also suggest that nonlinear ballistic
exciton transport due to the strong internal dipole pressure is readily
achievable.Comment: 5 pages, 4 figure
Fully guided electrically-controlled exciton polaritons
We demonstrate two types of waveguide structures which optically confine
exciton- polaritons in two dimensions and act as polaritonic channels. We show
a strong optical confinement in an etched rectangular waveguide, that
significantly increases the propa- gation distance of the polaritons and allow
to direct them in curved trajectories. Also, we show low-loss optical guiding
over a record-high of hundreds of microns which is com- bined seamlessly with
electrical control of the polaritons, in a strip waveguide formed by
electrically conductive and optically transparent strips deposited on top of a
planar waveguide. Both structures are scalable and easy to fabricate and offer
new possibilities for designing complex polaritonic devices.Comment: 12 pages 3 Figuer