Quantum dots introduce a new form of quantum engineering of materials properties based purely on size and dimensionality.Whereas we traditionally think of materials as having intrinsic properties such as strength,electrical conductivity and light absorption or emission spectra due to their composition and atomic-scale structure when their size is very small,such properties can be altered by quantummechanical effects,for example due to confinement of the quantum wavefunctions that determine the energies of charge carriers like electrons.