  Charge-neutral excitons in semiconductor quantum dots have a small finite
energy separation caused by the anisotropic exchange splitting. Coherent
excitation of neutral excitons will generally excite both exciton components,
unless the excitation is parallel to one of the dipole axes. We present a
polaron master equation model to describe two-exciton pumping using a coherent
continuous wave pump field in the presence of a realistic anisotropic exchange
splitting. We predict a five-peak incoherent spectrum, thus generalizing the
Mollow triplet to become a Mollow quintuplet. We experimentally confirm such
spectral quintuplets for In(Ga)As quantum dots and obtain very good agreement
with theory.

Mesoscale and Nanoscale Physics