It's not a hologram, of course. It's a stack of flat displays.
That's been tried before, in many ways. The first try was a vibrating mirror.[1] There's a flat rotating mirror system from FakeSpace.[2] It's not bad; you can walk around it. Move vertically, though, and the illusion breaks down. There's a scheme with gas ionized by intersecting laser beams. That's very low-rez, but truly volumetric.
Eventually, someone may come up with a real hologram system with decent resolution. A research group at MIT built one, but it was very low resolution and single-color. It's not impossible. But this isn't it.
I'm pretty impressed by what FOVI3D [1] has been doing w/ their light field displays. Here's a recent interview from SID Display Week this year [2] that's refreshing because the CTO (in the interview) goes into some of the details of the challenges they face and isn't unrealistic about how hard it'll be to overcome them.
There's also multi-planar rear-projection screens by Lightspace[1], they essentially have a stack of liquid crystal diffusers (20 or so) that can switch between transparent or diffusing state.
That's been tried before, in many ways. The first try was a vibrating mirror.[1] There's a flat rotating mirror system from FakeSpace.[2] It's not bad; you can walk around it. Move vertically, though, and the illusion breaks down. There's a scheme with gas ionized by intersecting laser beams. That's very low-rez, but truly volumetric.
Eventually, someone may come up with a real hologram system with decent resolution. A research group at MIT built one, but it was very low resolution and single-color. It's not impossible. But this isn't it.
[2] https://www.youtube.com/watch?v=8gvPS1m40gw