Sm. Sadeghi et Hm. Van Driel, Coherent control of the nonradiative decay of excitons in asymmetric quantum well structures - art. no. 045316, PHYS REV B, 6304(4), 2001, pp. 5316
We theoretically propose coherent control of the nonradiative decay of exci
tons in infrared-coupled asymmetric quantum wells. This is done by (i) indu
cing intraband multiphoton quantum coherences between exciton states associ
ated with three conduction subbands (E1, E2, and E3), and (ii) adjusting th
e contributions of these coherences using competition between one- and two-
photon coupling of these states. The intraband excitonic transitions are ca
used by one or two infrared laser beams resonant with the intersubband tran
sitions between E1, E2, and E3. We show that by tuning these beams to allow
coupling of the E1-HH1, E2-HH1, and E3-HH1 excitons with different configu
rations one can coherently manipulate the quantum efficiency of exciton emi
ssion. In an asymmetric double GaAs/AlxGa1-xAs quantum well this could lead
to nearly complete destruction of the emission spectrum, or to the immunit
y of excitons from enhancement of their nonradiative decay rates via the in
traband transitions. We discuss these effects in terms of coherent populati
on trapping of excitons and show how field-coherent destruction effects inf
luence the multiphoton excitonic coherences.