A new algorithm may give quantum computers a new, practical job: quickly solving monster linear equations. Such problems are at the heart of complex processes such as image and video processing, genetic analyses and even Internet traffic control.
...or Internet traffic scanning and analysis, we should add.
The new work, published October 7 in Physical Review Letters, may dramatically expand the range of potential uses for quantum computers.
An earlier version of the article: June 2, 2009
In the new study, Aram Harrow of the University of Bristol in England along with Avinatan Hassidim and Seth Lloyd, both of MIT, propose that large datasets of linear equations could be encoded in quantum forms, such as the spins of nuclei, individual atoms or photons. Such a system would allow quantum computers to handily solve problems made up of billions or even trillions of variables...
...thus raising the encryption bar even further. But, in the same issues of of Physical Review Letters and Science News, we find:
Entangled Photons Make Better Messengers
Quantum communication offers an absolutely secure way to send secret messages, such as encoded military secrets or financial transactions. But quantum information is fragile, quickly destroyed by even slight interactions with the environment.
While a conventional bit of information can have only one value, 0 or 1, a quantum bit, or qubit, exists as a combination of 0 and 1 simultaneously. A qubit stays in this undecided state until something, whether a stray atom or a scientist trying to measure its properties, interacts with it, forcing it into a single state. This collapse of possibilities, known as quantum decoherence, can be detected farther down the line to catch eavesdroppers. But it can also keep qubits from reaching their destination intact.
Fortunately, theorists have shown that some quantum-mechanical systems are immune to certain interactions...
Including eavesdropping?
