As an undergrad at GaTech (about to move on) who's looking to study quantum info (elsewhere) for my PhD, I'll tell you what I know. As far as I know, there are three groups at GT (other than GTRI) who are doing quantum info work, and really only two. Alex Kuzmich's lab does quantum optics with a focus on quantum telecommunications, and if that's what you're interested in they're pretty good at it and well respected. Ken Brown's group is attempting to do quantum information with trapped ions and molecules, and while they don't have too much to show for it yet, it's definitely interesting if that's your focus, and he's a great guy. On the other hand, the Georgia Tech Research Institute is looking to position itself as one of the main producers of Ion traps in the world. I'm not certain how one goes about doing your phd work with them, but I know someone who does. They're very serious about it, and have hired some real talent (e.g. Dr. Amini from NIST). I hope this is helpful.