Understanding slab foundation split in half

[Milind Shastri]

Hi folks, 

I'm a DIY'er myself and I picked the DIY section so I can learn from the experience of other hand-on folks. I'm trying to understand the approach to recommend to my foundation guy.

I'm working on a BRRR property with a foundation cracked along a straight line. Here's a picture and video explaining it.

It's as bad as this sample image: 

and here's a video of the crack: Video of crack

Wondering if anyone has any ideas of the approach to fix this. I know the foundation guys will be able to lift it up, but I'm trying to understand how to 'join' the cracked parts together so it can make a stable floor and be a reliable rental property.

Thanks!