A "switch" discovered by researchers at the University of Toronto in Canada could lead to the creation of an optical transistor. Aephraim Steinberg, Kevin Resch and Jeff Lundeen found that a BBO crystal lased with a 20-mW Ti:sapphire beam prohibits the simultaneous Resch said that one photon "turns the other off" in the crystal because of a quantum interference effect. The researchers hope the switch will enable development of an optical transistor that could allow computers to store and transfer information orders of magnitude faster by using photons instead of electrons.