Dipl.-Phys. Johannes David Plumhof

Strain-tuning of single semiconductor quantum dots

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http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-83517

Kurzfassung in Englisch

Polarization entangled photon pairs on demand are considered to be an important building block of quantum communication technology. It has been demonstrated that semiconductor quantum dots (QDs), which exhibit a certain spatial symmetry, can be used as a triggered, on-chip source of polarization entangled photon pairs. Due to limitations of the growth, the as-grown QDs usually do not exhibit the required symmetry, making the availability of post-growth tuning techniques essential. In this work first the QD-morphology of hundreds of QDs is correlated with the optical emission of neutral excitons confined in GaAs/AlGaAs QDs. It is presented how elastic anisotropic stress can be used to partially restore the symmetry of self-assembled GaAs/AlGaAs and InGaAs/GaAs QDs, making them as candidate sources of entangled photon pairs. As a consequence of the tuning of the QD-anisotropy we observe a rotation of the polarization of the emitted light. The joint modification of polarization orientation and QD anisotropy can be described by an anticrossing of the so-called bright excitonic states. Furthermore, it is demonstrated that anisotropic stress can be used to tune the purity of the hole states of the QDs by modifying the degree of heavy and light hole mixing. This ability might be interesting for applications using the hole spin as a so-called quantum bit.

weitere Metadaten

Schlagwörter
(Deutsch)
Quantenpunkte, Feinstrukturaufspaltung, Valenzbandmischung, verschraenkte Phtonenpaare, Ferroelektrischer Kristall
Schlagwörter
(Englisch)
quantum dots, excitonic fine structure splitting, gallium arsenide, strain, ferroelectric crystal, anticrossing, valence band mixing, entangled photon pairs
SWD SchlagworteQuantenpunkt, Halbleiter
DDC Klassifikation530
Institution(en) 
HochschuleTechnische Universität Chemnitz
FakultätFakultät für Naturwissenschaften
BetreuerProf. Dr. Oliver G. Schmidt
GutachterProf. Dr. Oliver G. Schmidt
Prof. Dr. Rudolf Bratschitsch
DokumententypDissertation
SpracheEnglisch
Tag d. Einreichung (bei der Fakultät)29.08.2011
Tag d. Verteidigung / Kolloquiums / Prüfung03.02.2012
Veröffentlichungsdatum (online)06.02.2012
persistente URNurn:nbn:de:bsz:ch1-qucosa-83517

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