Why use Photons instead of Electrons?
Answer: Because Light is faster than Electricity, Electrons have reached their physical limits.
Well yeah, umm, but the main point is missed and has to do with the basic difference between matter and energy.
Please understand that most any schoolkid knows what an atom is but a nuclear physicist doesn't. I don't pretend to be a nuclear physicist but I do know something of the lengthy effort to develop a photonics computer that has much in common with the effort to develop fusion power. I spent most of my professional life in a lab that was peripherally involved in such an effort. I have been retired for many years and please allow for obsolescence of knowledge as well.
If you grant that electrons are matter with mass - actually they are quite mysterious - and photons are pure energy without mass, you get to a key difference.
Cray used liquid nitrogen to cool his super computer to allow dense packing. I have no idea how current super computers deal with heat and other manifestations of the use of electrons in computing but such is not even a factor with photons that do not face the resistance found with super conductivity.
A photonics computer with a high-speed switch [a photonics transistor, so to speak] would instantly obsolete all electronic computers.
How close is LWLG?
I have no idea frankly but I surely am interested. How could anyone not be in a huge advance that would fulfill a decades-long dream?