Pyramidal quantum dots: single and entangled photon sources and correlation studies

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dc.contributor.advisor Pelucchi, Emanuele en Juska, Gediminas 2014-02-17T14:41:11Z 2015-02-18T05:00:05Z 2013 2013
dc.identifier.citation Juska, G. 2013. Pyramidal quantum dots: single and entangled photon sources and correlation studies. PhD Thesis, University College Cork. en
dc.identifier.endpage 121
dc.description.abstract Practical realisation of quantum information science is a challenge being addressed by researchers employing various technologies. One of them is based on quantum dots (QD), usually referred to as artificial atoms. Being capable to emit single and polarization entangled photons, they are attractive as sources of quantum bits (qubits) which can be relatively easily integrated into photonic circuits using conventional semiconductor technologies. However, the dominant self-assembled QD systems suffer from asymmetry related problems which modify the energetic structure. The main issue is the degeneracy lifting (the fine-structure splitting, FSS) of an optically allowed neutral exciton state which participates in a polarization-entanglement realisation scheme. The FSS complicates polarization-entanglement detection unless a particular FSS manipulation technique is utilized to reduce it to vanishing values, or a careful selection of intrinsically good candidates from the vast number of QDs is carried out, preventing the possibility of constructing vast arrays of emitters on the same sample. In this work, site-controlled InGaAs QDs grown on (111)B oriented GaAs substrates prepatterned with 7.5 μm pitch tetrahedrons were studied in order to overcome QD asymmetry related problems. By exploiting an intrinsically high rotational symmetry, pyramidal QDs were shown as polarization-entangled photon sources emitting photons with the fidelity of the expected maximally entangled state as high as 0.721. It is the first site-controlled QD system of entangled photon emitters. Moreover, the density of such emitters was found to be as high as 15% in some areas: the density much higher than in any other QD system. The associated physical phenomena (e.g., carrier dynamic, QD energetic structure) were studied, as well, by different techniques: photon correlation spectroscopy, polarization-resolved microphotoluminescence and magneto-photoluminescence. en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2013, Gediminas Juska. en
dc.rights.uri en
dc.subject Quantum dots en
dc.subject Polarization-entangled photons en
dc.subject.lcsh Quantum theory en
dc.subject.lcsh Photons en
dc.title Pyramidal quantum dots: single and entangled photon sources and correlation studies en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PhD (Science) en
dc.internal.availability Full text available en
dc.description.version Accepted Version
dc.contributor.funder Science Foundation Ireland en
dc.description.status Not peer reviewed en Physics en
dc.check.reason This thesis is due for publication or the author is actively seeking to publish this material en
dc.check.opt-out No en
dc.thesis.opt-out false
dc.check.entireThesis Entire Thesis Restricted
dc.check.embargoformat E-thesis on CORA only en
dc.internal.conferring Spring Conferring 2014 en

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© 2013, Gediminas Juska. Except where otherwise noted, this item's license is described as © 2013, Gediminas Juska.
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