Well all the info is in the article so off you go if you want technical specifications.
In Japan they use QR codes for anti theft so something around this size would probably work:
QR codes are read by a scanner as you well know, so not only is this a foolproof technology for identifying a bicycle, it also ensures only legitimate cases with footage can actually be reported. The QR code can be read with 100% success rate at the speed a bicycle travels.
Surely this is a plus for those of us worried about big brother, privacy issues or the danger of malicious or vexatious reports.
I dont see why this would be such an issue if you are following the rules of the road.