  Optical response of artificial composite nanoscale molecules comprising a
closely spaced noble metal nanoparticle and a semiconductor quantum dot have
been studied theoretically. We consider a system composed of an Au particle and
CdSe or CdSe/ZnSe quantum dot and predict optical bistability and hysteresis in
its response, which suggests various applications, in particular, all-optical
processing and optical memory.

Quantum Physics;Optics