 |
Quantum Cryptography
Quantum Cryptography
In quantum key distribution (QKD), two parties use single photons that
are randomly polarized to states representing ones and zeroes to transmit a
series of random number sequences that are used as keys in cryptographic
communications. This string of numbers becomes a quantum key that locks
or unlocks encrypted messages sent via normal communication channels.
Because the transmitted photons cannot be intercepted without being
destroyed, and the act of interception then tips off the message receiver,
QKD is considered the most powerful data encryption scheme ever developed
and its codes are, by all indications, virtually unbreakable.
World Record
Although the quantum key distribution technique was not created at
Los Alamos, laboratory researchers have taken the technology, quite literally,
to new lengths in the interest of national security. In 1999, Los Alamos
researchers set a world record when they sent a quantum key through a
31-mile-long optical fiber. While this distance proved sufficiently far enough
to create QKD networks connecting closely-spaced government offices or
localized bank branches, the system failed at greater distances when signal loss
increased to the point at which the photons were absorbed by normal optical
fiber noise. To achieve longer distances, Los Alamos researchers developed a
free-space quantum cryptography system that could send keys through the air.
Los Alamos quantum scientists developed a transportable, self-contained
QKD system that used polarized photons to send information through the
air for distances of up to 10 miles.
This mobile trailer-based QKD system could be quickly deployed in the field and was capable of continuous,
automated transmission in both daylight and darkness. Today, Los Alamos
researchers are in the process of taking this technology even further by
developing a smaller scale version that is capable of being put on an Earthorbiting
satellite for transmitting quantum keys distances of hundreds of
miles between the satellite and a ground station.
|
Newsworthy
|
