"They would also like to use electricity rather than light to excite the nanocube"
And therein lies the catch: They excite a system containing quantum dots and silver nanoparticles with a 150 femtosecond laser. The laser pulse has extraordinarily high intensities (up to 10^7 W/(square cm)) and they get some light back out on the picosecond time scale. The emission time is some 2 orders of magnitude slower than the laser pulse duration.
It is not clear at all how they want to electrically excite the system. Illuminating a controlled area with high intensity light is easy (if you have a >>10^5 $ laser), but getting the same amount of energy into the system electrically and within a few 100 femtoseconds is a completely different problem.
So don't get your hopes up, somebody still has to crack a lot of hard problems before you can buy a 100 GHz optical computer.