Recent advances in material fabrication techniques

analytic tools and computational power have greatly enhanced the prospect of making electrons and photons work

respectively

in their best roles

10

12

bit/s operating speed might be reached. Two basic research questions arise: （i） what are the configurational

physical

and material constraints which prevent devices from operating at this speed

and can these constraints be altered? （ii）If 10

12

bit/s can indeed be reached

what system functional building blocks should be generated ? Research directions in this area are suggested.