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SUMMARY:Control of electronic and optical properties of single and double 
 quantum dots via growth and electroelastic fields - Dr Eugenio Zallo\, Ins
 titute for Integrative Nanosciences\, IFW Dresden\, Germany
DTSTART:20141210T134500Z
DTEND:20141210T144500Z
UID:TALK56667@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:Semiconductor quantum dots (QDs) are fascinating systems for p
 otential applications in quantum information processing and communication\
 , since they can emit single photons and\, under certain conditions\, pola
 risation entangled photons pairs on demand. The asymmetry and inhomogeneit
 y of real QDs has driven the development of a universal and fine post-grow
 th tuning technique. In parallel\, new growth methods are desired to creat
 e QDs with high emission efficiency and to control combinations of closely
  spaced QDs\, so-called “QD molecules” (QDMs).\n\nThese systems are cr
 ucial for the realisation of a scalable information-processing device afte
 r a tuning of their interaction energies. In this talk\, a growth method b
 ased on the infilling of droplet etched nanoholes for obtaining high optic
 al quality and widely tuneable emission wavelength GaAs/AlGaAs QDs and for
  controlling the lateral formation of InGaAs QD pairs is shown. A novel sa
 mple structure permits the light hole to be switched to the ground state b
 y elastically stressing an initially unstrained GaAs QD.\n\nThen\, the fir
 st device allowing the QD and QDM emission properties to be engineered by 
 large strain and electric fields is presented. This is obtained by integra
 ting diode‐like nanomembranes onto piezoelectric actuators containing si
 ngle SK-InGaAs/GaAs QDs and QDMs. The two external fields allow the genera
 tion of entangled photons by a universal recovery of the QD symmetry and t
 he coupling strength in vertically aligned QDMs to be actively tuned. Thes
 e results are relevant for the creation and control of entangled states an
 d may enable controlled quantum operations.\n
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics
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