arXiv subjects

J. -Ph. Poizat

Publications and source records attributed to J. -Ph. Poizat.

3 recordsLinked to original sources

arXiv2018

Static strain tuning of quantum dots embedded in a photonic wire

We use strain to statically tune the semiconductor band gap of individual InAs quantum dots (QDs) embedded in a GaAs photonic wire featuring very efficient single photon collection efficiency. Thanks to the geometry of the structure, we are able to shift the QD excitonic transition by more than 20 meV by using nano-manipulators to apply the stress. Moreover, owing to the strong transverse strain gradient generated in the structure, we can relatively tune two QDs located in the wire waveguide and bring them in resonance, opening the way to the observation of collective effects such as superradiance.

cond-mat.mes-hall↗

arXiv2011

Exciton-phonon coupling efficiency in CdSe quantum dots embedded in ZnSe nanowires

Exciton luminescence of a CdSe quantum dot (QD) inserted in a ZnSe nanowire is strongly influenced by the dark exciton states. Because of the small size of these QDs (2-5nm), exchange interaction between hole and electron is highly enhanced and we measured large energy splitting between bright and dark exciton states ($ΔE\in [4, 9.2 ]$ meV) and large spin flip rates between these states. Statistics on many QDs showed that this splitting depends on the QD size. Moreover, we measured an increase of the spin flip rate to the dark states with increasing energy splitting. We explain this observation with a model taking into account the fact that the exciton-phonon interaction depends on the bright to dark exciton energy splitting as well as on the size and shape of the exciton wave function. It also has consequences on the exciton line intensity at high temperature.

cond-mat.mes-hall↗

arXiv2011

Subnanosecond spectral diffusion of a single quantum dot in a nanowire

We have studied spectral diffusion of the photoluminescence of a single CdSe quantum dot inserted in a ZnSe nanowire. We have measured the characteristic diffusion time as a function of pumping power and temperature using a recently developed technique [G. Sallen et al, Nature Photon. \textbf{4}, 696 (2010)] that offers subnanosecond resolution. These data are consistent with a model where only a \emph{single} carrier wanders around in traps located in the vicinity of the quantum dot.

cond-mat.mes-hall↗