Personally, I find Nielsen and Chuang (Mike and Ike as it's affectionately referred to in the field) to be a good reference, but not great for learning the topic the first time. It's also expensive. I think that Rieffel and Polak [0] is a little easier to follow, and surprisingly thorough for an introductory book. Note, there is no reason to buy a book though, as John Preskill has his notes online [1], which I often see cited in published manuscripts.
This reminds me of the first robot bird http://ed.ted.com/on/xtyd4M5V that was built a few years ago. I would be interested in knowing how difficult it is to build a robot bat once you already know how to build a robot bird. Is there any specific challenge in emulating the way bats fly compared to birds?