Ultrafast atomic-scale visualization of acoustic phonons generated by optically excited quantum dots
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...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
AIP Publishing LLC and ACA
2017-07-01
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| Series: | Structural Dynamics |
| Online Access: | http://dx.doi.org/10.1063/1.4998009 |
| _version_ | 1819147181060259840 |
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| author | Giovanni M. Vanacore Jianbo Hu Wenxi Liang Sergio Bietti Stefano Sanguinetti Fabrizio Carbone Ahmed H. Zewail |
| author_facet | Giovanni M. Vanacore Jianbo Hu Wenxi Liang Sergio Bietti Stefano Sanguinetti Fabrizio Carbone Ahmed H. Zewail |
| author_sort | Giovanni M. Vanacore |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-12-22T13:25:44Z |
| format | Article |
| id | doaj.art-0761fe8c4e0a48eca5d50f9e3ee04048 |
| institution | Directory Open Access Journal |
| issn | 2329-7778 |
| language | English |
| last_indexed | 2024-12-22T13:25:44Z |
| publishDate | 2017-07-01 |
| publisher | AIP Publishing LLC and ACA |
| record_format | Article |
| series | Structural Dynamics |
| spelling | doaj.art-0761fe8c4e0a48eca5d50f9e3ee040482022-12-21T18:24:18ZengAIP Publishing LLC and ACAStructural Dynamics2329-77782017-07-0144044034044034-1010.1063/1.4998009033795SDYUltrafast atomic-scale visualization of acoustic phonons generated by optically excited quantum dotsGiovanni M. Vanacore0Jianbo Hu1Wenxi Liang2Sergio Bietti3Stefano Sanguinetti4Fabrizio Carbone5Ahmed H. Zewail6 Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USA Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USA Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USA L-NESS and Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Via Cozzi 53, I-20125 Milano, Italy L-NESS and Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Via Cozzi 53, I-20125 Milano, Italy Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USAUnderstanding 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.http://dx.doi.org/10.1063/1.4998009 |
| spellingShingle | Giovanni M. Vanacore Jianbo Hu Wenxi Liang Sergio Bietti Stefano Sanguinetti Fabrizio Carbone Ahmed H. Zewail Ultrafast atomic-scale visualization of acoustic phonons generated by optically excited quantum dots Structural Dynamics |
| title | Ultrafast atomic-scale visualization of acoustic phonons generated by optically excited quantum dots |
| title_full | Ultrafast atomic-scale visualization of acoustic phonons generated by optically excited quantum dots |
| title_fullStr | Ultrafast atomic-scale visualization of acoustic phonons generated by optically excited quantum dots |
| title_full_unstemmed | Ultrafast atomic-scale visualization of acoustic phonons generated by optically excited quantum dots |
| title_short | Ultrafast atomic-scale visualization of acoustic phonons generated by optically excited quantum dots |
| title_sort | ultrafast atomic scale visualization of acoustic phonons generated by optically excited quantum dots |
| url | http://dx.doi.org/10.1063/1.4998009 |
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