Speaker
Mr
Pranai Vasudev
(University of Toronto)
Description
While normally quantum mechanical effects are observable at cryogenic
temperatures and at very small length scales, our work brings these
quantum phenomena to the macroscopic length scale and to room
temperature. Our work focuses on the possibility of room-temperature
thermal equilibrium Bose-Einstein condensation (BEC) of quantum well
exciton-polaritons in micrometer scale cavities composed of photonic
band gap materials. Using cavities composed of double slanted pore
(SP2) photonic crystals embedded with InGaAs quantum wells, we predict
the formation of a 10 $\mu$m to 1 cm sized thermal equilibrium
Bose-Einstein condensate at room temperature that allows for the
emission of light near the telecommunications band of $\sim$1300
nm. The three-dimensional photonic band gap of the SP2 crystal allows
for light to be strongly confined to the quantum wells, resulting in
strong light-matter coupling in the exciton-polaritons and vacuum Rabi
splittings that are $\sim$2% of the bare exciton recombination
energy. The photonic band gap also strongly inhibits the radiative
decay of the exciton-polaritons and due to the slow non-radiative
decay of excitons as well as fast exciton-phonon scattering in InGaAs
at room temperature, the exciton-polaritons that form the BEC are able
to reach thermal equilibrium with their host lattice. We consider
three InGaAs quantum wells (of width 3 nm surrounded by 7 nm InP
barriers) judiciously placed in a 33 nm cavity between SP2 crystals
with a lattice constant of 471 nm and polaritons consisting of a
superposition of excitons and photons that are tuned below the
excitonic recombination energy. This detuning increases the
polariton's dispersion depth and increases the number of available
photon-like states to enhance the formation of a BEC. We predict the
onset of a BEC at a temperature of 364 K in a box-trap of side length
10 $\mu$m at a polariton density of $1.6\times10^{11}$ cm$^{-2}$,
indicating that a room temperature, thermal equilibrium BEC can be
obtained with light emission near the telecommunications band.
Author
Mr
Pranai Vasudev
(University of Toronto)
Co-authors
Dr
Jian Hua Jiang
(University of Toronto)
Prof.
Sajeev John
(University of Toronto)
