It's a holgram that can be viewed with visible light but is 60nm thick
(Unless you can in the deep UV end of the spectrum, in which you probably need a mask and costume)
It's made by making a "phase" or thickness hologram in the film by blasting away dots of the film with a laser. dots are 2 micrometers square at 800nm. 3mm x 3mm takes 1500 x 1500 pixels. It's made on Silicon so I guess it's viewed in reflection.
You can view the hologram by illuminating it with light at RGB wavelengths. I'm not sure if you illuminate it with 3 beams simultaneously you get the 3 images to line up.
So they've demonstrated quantum effects in the film that lets a film 1/7.4 to 1/10 the thickness of the illuminating light act as a hologram to light at that frequency. But you can't erase it or rewrite it.
Rewritable holograms have been done with plastic films (heat them to soften) or crystals (Pockels Read Out Memory PROM) using a laser write/high voltage erase cycle.
Apart from the quantum science aspect my reaction is "So what?" They've show the phenomena works on this material but the write method is b**ger all use in any sort of display. IOW it's v 0.1 tech.
For those who study quantum mechanics of materials or the construction of "metamaterials" with novel refractive index properties this is no doubt very impressive.
The fantasy of holographic displays is a flat unit you can lay down somewhere and get a large full colour display in front of you. But most computer applications need primarily that to be a 2d image. That puts a lot of data in 1 plane of that image and that plane is at 90deg to the emitter.
People have made cell phones with micro projectors in them to do that.
How well did they sell?