Hi,
I bought the same monitor. I will receive it next week, but i read some blogs about the best alternatives for getting the 2560x1440 and my first option will be connecting my macbook pro retina 13' using the thunderbolt (mini-display port) to the mini-display port available in the monitor.
I'm planning using this cable:
http://store.apple.com/us/product/MD862ZM/A/apple-thunderbolt-cable-05-m
A mini-reference about the mini-display port (It was useful for me):
Apple Mini DisplayPort adapters: Frequently asked questions (FAQ) - Apple Support
This is what I'm planning to do. Note that I don't know if it works! I think so, but I don't know. I will tell you if it works next week.
If you have a mini-display port to display port cable it should work too.
Regards,
Carlos.