  The measurable degree of entanglement from a quantum dot via the
biexciton-exciton cascade depends crucially on the bright exciton
fine-structure splitting and on the detection time resolution. Here, we propose
an optical approach with fast rotating waveplates to erase this fine-structure
splitting and therefore obtain a high degree of entanglement with near-unity
efficiency. Our optical approach is possible with current technology and is
also compatible with any quantum dot showing fine-structure splitting.
