| Title: |
Ultrafast atomic-scale visualization of acoustic phonons generated by optically excited quantum dots |
| Authors: |
Giovanni M. Vanacore, Jianbo Hu, Wenxi Liang, Sergio Bietti, Stefano Sanguinetti, Fabrizio Carbone, Ahmed H. Zewail |
| Source: |
Structural Dynamics, Vol 4, Iss 4, Pp 044034-044034-10 (2017) |
| Publisher Information: |
AIP Publishing LLC and ACA, 2017. |
| Publication Year: |
2017 |
| Collection: |
LCC:Crystallography |
| Subject Terms: |
Crystallography, QD901-999 |
| More Details: |
Understanding the dynamics of atomic vibrations confined in quasi-zero dimensional systems is crucial from both a fundamental point-of-view and a technological perspective. Using ultrafast electron diffraction, we monitored the lattice dynamics of GaAs quantum dots—grown by Droplet Epitaxy on AlGaAs—with sub-picosecond and sub-picometer resolutions. An ultrafast laser pulse nearly resonantly excites a confined exciton, which efficiently couples to high-energy acoustic phonons through the deformation potential mechanism. The transient behavior of the measured diffraction pattern reveals the nonequilibrium phonon dynamics both within the dots and in the region surrounding them. The experimental results are interpreted within the theoretical framework of a non-Markovian decoherence, according to which the optical excitation creates a localized polaron within the dot and a travelling phonon wavepacket that leaves the dot at the speed of sound. These findings indicate that integration of a phononic emitter in opto-electronic devices based on quantum dots for controlled communication processes can be fundamentally feasible. |
| Document Type: |
article |
| File Description: |
electronic resource |
| Language: |
English |
| ISSN: |
2329-7778 |
| Relation: |
https://doaj.org/toc/2329-7778 |
| DOI: |
10.1063/1.4998009 |
| Access URL: |
https://doaj.org/article/0761fe8c4e0a48eca5d50f9e3ee04048 |
| Accession Number: |
edsdoj.0761fe8c4e0a48eca5d50f9e3ee04048 |
| Database: |
Directory of Open Access Journals |
