Position-Based Quantum Cryptography

Here's an interesting paper: Position-Based Quantum Cryptography by Nishanth Chandran, Serge Fehr, Ran Gelles, Vipul Goyal, and Rafail Ostrovsky.You can get the paper here on arXiv and there is a good popular science summary here on Technology Review. Quantum cryptography has some great applications, adding in location makes it even more so.