Experimental quantum key distribution based on a Bell test
  We report on a complete free-space field implementation of a modified Ekert91 protocol for quantum key distribution using entangled photon pairs. For each photon pair we perform a random choice between key generation and a Bell inequality. The amount of violation is used to determine the possible knowledge of an eavesdropper to ensure security of the distributed final key. 
Alexander Ling, Matthew P. Peloso, Ivan Marcikic, Valerio Scarani,   Antia Lamas-Linares, Christian Kurtsiefer