Dynamics of coherent and incoherent spin polarizations in ensembles of quantum dots.
The temperature dependence of spin coherence in InGaAs quantum dots is obtained from quantum beats observed in polarization-resolved pump-probe experiments. Within the same sample we clearly distinguish between coherent spin dynamics leading to quantum beats and incoherent long-lived spin-memory effects. Analysis of the coherent data using a theoretical model reveals approximately 10 times greater stability of the spin coherence at high temperature compared to that found previously for exciton states in four-wave-mixing experiments by Borri et al. [Phys. Rev. Lett. 87, 157401 (2001)]]. The data on incoherent polarization reveal a new form of spin memory based on charged quantum dots.
Tartakovskii
A I
AI
Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom.
Cahill
J
J
Makhonin
M N
MN
Whittaker
D M
DM
Wells
J-P R
JP
Fox
A M
AM
Mowbray
D J
DJ
Skolnick
M S
MS
Groom
K M
KM
Steer
M J
MJ
Hopkinson
M
M