Nature:
In theory, sending quantum-encrypted messages is secure because
any attempt at snooping is apparent to the recipient. In
practice, the physical systems that encrypt the messages are
imperfect. Noise creeps in. Still, until now, physicists had
believed that if noise remained below 20%, snooping would be
exposed. The University of Toronto's Feihu Xu, Bing Qi, and
Hoi-Kwong Lo have
devised a method
to intercept quantum encrypted communication while remaining
below the 20% detection threshold.
