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| 3. |
- Byszewski, M., et al.
(författare)
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Magneto-photoluminescence of heavy- and light-hole excitons in site-controlled pyramidal quantum dots
- 2008
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Ingår i: Physica. E, Low-Dimensional systems and nanostructures. - : Elsevier BV. - 1386-9477 .- 1873-1759. ; 40:6, s. 1873-1875
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Tidskriftsartikel (refereegranskat)abstract
- Pyramidal, site-controlled InGaAs/AlGaAs quantum dots (QDs) are studied by micro-photoluminescence (PL) spectroscopy in a magnetic field. The light-hole (LH) excitonic transitions exhibit diamagnetic shifts similar to those of their heavy-hole (HH) counterparts. From the evolution of the excitonic lines, effective g-factors of g=1.7 and 0.4 for HH and LH neutral excitons are inferred
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| 4. |
- Dupertuis, Marc-André, et al.
(författare)
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Nanostructure symmetry : Relevance for physics and computing
- 2014
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Ingår i: AIP Conference Proceedings. - : AIP Publishing LLC. - 0094-243X.
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Konferensbidrag (refereegranskat)abstract
- We review the research done in recent years in our group on the effects of nanostructure symmetry, and outline its relevance both for nanostructure physics and for computations of their electronic and optical properties. The exemples of C3v and C2v quantum dots are used. A number of surprises and non-trivial aspects are outlined, and a few symmetry-based tools for computing and analysis are shortly presented.
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| 5. |
- Dupertuis, M A, et al.
(författare)
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Symmetries and the Polarized Optical Spectra of Exciton Complexes in Quantum Dots
- 2011
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 107:12, s. 127403-
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Tidskriftsartikel (refereegranskat)abstract
- A systematic and simple theoretical approach is proposed to analyze true degeneracies and polarized decay patterns of exciton complexes in semiconductor quantum dots. The results provide reliable spectral signatures for efficient symmetry characterization, and predict original features for low C(2 nu) and high C(3 nu) symmetries. Excellent agreement with single quantum dot spectroscopy of real pyramidal InGaAs/AlGaAs quantum dots grown along [111] is demonstrated. The high sensitivity of biexciton quantum states to exact high symmetry can be turned into an efficient uninvasive postgrowth selection procedure for quantum entanglement applications.
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| 7. |
- Karlsson, Fredrik, et al.
(författare)
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Fine structure of exciton complexes in high-symmetry quantum dots: Effects of symmetry breaking and symmetry elevation
- 2010
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Ingår i: PHYSICAL REVIEW B. - : American Physical Society. - 1098-0121. ; 81:16, s. 161307-
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Tidskriftsartikel (refereegranskat)abstract
- Quantum dots (QDs) of high symmetry (e.g., C-3 nu) have degenerate bright exciton states, unlike QDs of C-2 nu symmetry, making them intrinsically suitable for the generation of entangled photon pairs. Deviations from C-3 nu symmetry are detected in real QDs by polarization-resolved photoluminescence spectroscopy in side-view geometry of InGaAs/AlGaAs dots formed in tetrahedral pyramids. The theoretical analysis reveals both an additional symmetry plane and weak symmetry breaking, as well as the interplay with electron-hole and hole-hole exchange interactions manifested by the excitonic fine structure.
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| 9. |
- Karlsson, Fredrik, 1974-, et al.
(författare)
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Optical polarization anisotropy and hole states in pyramidal quantum dots
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89, s. 251113-
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Tidskriftsartikel (refereegranskat)abstract
- The authors present a polarization-resolved photoluminescence study of single semiconductor quantum dots (QDs) interconnected to quantum wires, measured both in a top geometry, and in a less conventional cleaved-edge geometry. Strong polarization anisotropy is revealed for all observed transitions, and it is deduced that closely spaced QD hole states exhibit nearly pure heavy-or light-hole character. These effects are attributed to the large aspect ratio of the dot shape
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| 10. |
- Karlsson, K Fredrik, et al.
(författare)
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Spectral signatures of high-symmetry quantum dots and effects of symmetry breaking
- 2015
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Ingår i: New Journal of Physics. - : Institute of Physics Publishing (IOPP). - 1367-2630. ; 17:10
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Tidskriftsartikel (refereegranskat)abstract
- High symmetry epitaxial quantum dots (QDs) with three or more symmetry planes provide a very promising route for the generation of entangled photons for quantum information applications. The great challenge to fabricate nanoscopic high symmetry QDs is further complicated by the lack of structural characterization techniques able to resolve small symmetry breaking. In this work, we present an approach for identifying and analyzing the signatures of symmetry breaking in the optical spectra of QDs. Exciton complexes in InGaAs/AlGaAs QDs grown along the [111]B crystalline axis in inverted tetrahedral pyramids are studied by polarization resolved photoluminescence spectroscopy combined with lattice temperature dependence, excitation power dependence and temporal photon correlation measurements. By combining such a systematic experimental approach with a simple theoretical approach based on a point-group symmetry analysis of the polarized emission patterns of each exciton complex, we demonstrate that it is possible to achieve a strict and coherent identification of all the observable spectral patterns of numerous exciton complexes and a quantitative determination of the fine structure splittings of their quantum states. This analysis is found to be particularly powerful for selecting QDs with the highest degree of symmetry ( C 3 v and ##IMG## [http://ej.iop.org/images/1367-2630/17/10/103017/njp519062ieqn1.gif] $D_3h$ ) for potential applications of these QDs as polarization entangled photon sources. We exhibit the optical spectra when evolving towards asymmetrical QDs, and show the higher sensitivity of certain exciton complexes to symmetry breaking.
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