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SUMMARY:Optical control and dynamics of a single Mn spin in a CdTe/ZnTe qu
 antum dot - Claire Le Gall (Grenoble)
DTSTART:20110516T143000Z
DTEND:20110516T160000Z
UID:TALK31303@talks.cam.ac.uk
CONTACT:6270
DESCRIPTION:A Manganese Atom is added in the CdTe crystal of a II-VI quant
 um dot\, forming a 5/2 localised spin. The spd-exchange interactions betwe
 en this Mn atom and a photo-created electron-hole pair results in the emis
 sion of a photon at a given energy depending on the spin-state of the Mn a
 tom [1]. In other words\, it is possible to access optically the Mn spin-s
 tate. We will show in this talk that it is possible to control the orienta
 tion of the Mn spin optically using quasi-resonant excitation [2] or reson
 ant excitation [3]. The pumping process is directly observed through time-
 resolved experiments. Relaxation of the Mn spin can be accessed optically 
 and T1 is found to be much longer than 10 micro-seconds. We will discuss t
 he physics ruling this process: the observed Mn optical orientation can be
  explained by carrier spin-relaxation towards dark states as proposed by L
 . Cyvinsky in [4]\, in conjunction with a strained-induced crystal field a
 long the growth axis that guarantees the conservation of the Mn spin-state
  Sz between the injection of two excitons even at B=0T. At last\, we will 
 report on the observation of optically dressed states and optical stark ef
 fect performed on any given spin-state of the Mn atom [5]\, which is a fir
 st step toward a coherent control of the Mn spin.\n\n[1] L. Besombes\, Y. 
 Leger\, L. Maingault\, D. Ferrand\, H. Mariette "Probing the spin state of
  a single Magnetic ion in an individual quantum dot" Phys Rev Lett 93\, 20
 7403 (2004)\n\n[2] C. Le Gall\, L. Besombes\, H. Boukari\, R. Kolodka\, J.
  Cibert\, and H. Mariette "Optical Spin Orientation of a Single Manganese 
 Atom in a Semiconductor Quantum Dot Using Quasiresonant Photoexcitation"\,
  Phys Rev Lett 102\, 127402 (2009)\n\n[3] C. Le Gall\, R. S. Kolodka\, C. 
 L. Cao\, H. Boukari\, H. Mariette\, J. Fernández-Rossier\, and L. Besombe
 s "Optical initialization\, readout\, and dynamics of a Mn spin in a quant
 um dot" Phys Rev B 81\, 245315 (2010)\n\n[4] L. Cyvinski\, "Optical orient
 ation of a single Mn spin in a quantum dot: Role of carrier spin relaxatio
 n"\, Phys Rev B 82\, 075321 (2010) \n\n[5] C. Le Gall\, A. Brunetti\, H. B
 oukari\, L. Besombes\, "Optical Stark Effect and Dressed Excitonic States 
 in a Mn-doped Quantum Dot" http://arxiv.org/abs/1104.3026\n\n \n\n
LOCATION:Rutherford building\, Seminar Room B
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