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SUMMARY:Quantum information exchange between photons and electrons in soli
 ds - Hideo Kosaka (Tohoku Univeristy\, Japan)
DTSTART:20100505T130000Z
DTEND:20100505T140000Z
UID:TALK23934@talks.cam.ac.uk
CONTACT:6270
DESCRIPTION:Spin is a fundamental property of electrons and plays an impor
 tant role in information storage. For spin-based quantum information techn
 ology\, write (preparation) and read-out (measurement) processes of the el
 ectron spin state should be coherent. However\, both the traditional write
  and read-out processes were projections to up/down spin states\, which do
  not preserve spin coherence. We have recently demonstrated that we can tr
 ansfer the polarization coherence of light to the spin coherence of electr
 ons in a semiconductor quantum nanostructure [1]\, and we can also read ou
 t the prepared coherence of the electron spin optically by the developed t
 omographic Kerr rotation (TKR) method [2]. In these demonstrations\, it wa
 s important to set the g-factor of an electron to be nearly zero. We have 
 also demonstrated that the spin coherence of a single electron trapped in 
 a gate-defined quantum dot\, where the g-factor of electrons is tuned to n
 early zero\, can be electrically manipulated with a microwave applied to t
 he gate utilizing electric-dipole spin resonance (EDSR) [3]. The fabricate
 d quantum dot with a point contact as a charge sensor evidenced that a sin
 gle electron is actually created by the absorbed photon in the dot [4]. We
  have also theoretically shown that two-electron coherence can be manipula
 ted and measured via spin-flip tunneling with the help of the spin-orbit i
 nteraction [5]. Furthermore\, we have shown that the full Bell-state measu
 rement needed for the quantum repeater can even be achieved with help of g
 -factor engineering and g-factor switching [6].\n\n[1] H. Kosaka et al. Ph
 ys. Rev. Lett. 100\, 096602 (2008).\n[2] H. Kosaka et al. Nature 457\, 702
  (2009). \n[3] T. Kutsuwa et al.\, Physica E\, 42\, 821 (2010).\n[4] M. Ku
 wahara et al.\, App. Phys. Lett.\, to be published.\n[5] N. Yokoshi et al.
 \, Phys. Rev. Lett. 103\, 046806 (2009).\n[6] N. Yokoshi et al.\, Phys. Re
 v. B Rapid Communications\, to be published.\n
LOCATION:Rutherford building\, Seminar Room B
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