Inquiring minds want to knowQuantum encryption: Inherently unbreakable or vulnerbale to hacking?

We recently wrote two stories about quantum encryption which appear to give contradictory answer to this question. In the 5 June issue we wrote of a Stanford lab experiment with record-setting transmition of “quantum keys” over 200 kilometers of fiber optic link, adding that “If properly executed, quantum encryption is unbreakable because eavesdropping changes the state of the photons.” Yet, in our 27 April issue, we reported that an MIT team was able to hack a quantum encryption-protected network. We quoted Professor Jeffrey Shapiro, who said that while the hack the tram used was not good enough to break commercial systems, the team expected “that one day it will be able to do so, if quantum encryption isn’t adequately adapted to stop such hackers from succeeding.”

Now, is it the case that “adequately adapted” and “properly executed” refer to the same thing? “Properly executed” appears to imply that there is an inherent unbreakability to quantum encryption, while “adequately adapted” appears to imply that quantum encryption must be tweaked and modified in order to be immune to breaking.

The ever-alert Ken Cornett of Motorola drew our attention to the tension between the implications of the two stories. On Monday we will report on another impressive transmission of quantum keys over distance: A team of researchers was able to create an encryption key in two locations simultaneously — one in a lab on La Palma, in the Canary Islands, and the second in an observatory on the neighboring island of Tenerife, 144 kilometers away. As we describe the experiment, we will address the question of the technology’s inherent unbreakability.

-read more about the Canary Islands experiment in R. Ursin et. al, “Entanglement-based Quantum Communication Over 144 km,” Nature Physics (3 June 2007) (sub. req.)