Ann Arbor (MI) - University of Michigan scientists have discovered a breakthrough way to utilize light in cryptography. The new technique can crack even complex codes in a matter of seconds. Scientists believe this technique offers much advancement over current solutions and could serve to foil national and personal security threats if employed.

The process involves extremely short pulses of coherent light being emitted and interacting with something called "quantum dots". Quantum dots are mystic pieces of "science fluff" to most people as they're difficult to understand: Basically, they are very small structures that are sensitive to very small changes.  By adjusting the frequencies and phase shifting the light in a more complex system, the beam itself forms a kind of "optical network" with compute abilities as it passes by the quantum dots.

When the final theorized device is constructed, one requiring potentially many thousands of quantum dots (the exact number is a matter of scientific debate right now), the light beam itself will be encoded with the equivalent of a query.  This will be something like a factorization of a numbers or number sequence to "lookup".  It is then "sent" to the quantum dot where all possible answers are computed.  The answers are then immediately "read" on the far side.  By encoding sequence after sequence in this way, answers to even extremely complex problems, those which might take dozens of years to solve using modern high-end desktop computers today, can be computed in seconds.

One advantage of this particular approach is that very inexpensive diode lasers are used as the light source.  The maximum sustainable switching rates are theorized around 100 GHz with operational frequencies in the lab of 1.4 GHz.  Future devices using this technology could be created in three dimensions due to the extremely low heat generation.  Only a single photon is required to make the optical gate (qubit) switch.  The energy used to switch the qubit is 10^-18 joules.  In other words, to operate at 1 GHz requires only 1 billionth of a watt.  A competing line of research in this area comes from the the Trapped Ion (TI) approach which operates in a large vacuum.  It is believed TI will prove more likely for initial success, though its computing power is several orders of magnitude lower than this approach.  The eventual products coming out of this solution have the capability of being the technological equivalent of Core 2 Duos or Opterons as compared to the ENIAC they have working in the lab today.

Researchers are currently working on future uses of this technology.  These include "quantum dot dressed state lasers, optical modulators and quantum logic devices," which would serve as the foundation of viable future quantum computers.  This project was funded by the National Security Agency (NSA), the Army Research Office, Air Force Office of Scientific Research and Naval Research Labs.  The research for this project was carried out by Duncan Steel and three senior researchers as well as about ten undergrad students.  Research work was spread out and shared between different sites.  The University of San Diego handled the theory.  The Naval Research Labs handled the quantum dot physics.  And the University of Michigan worked on the compute portion.  Similar joint efforts will continue once the number of quantum dots to use in an actual application is discovered.  The project receives approximately $800,000 per year in funding.

Full details will be published tomorrow in the August 17 issue of Science Magazine in an article is entitled "Coherent Optical Spectroscopy of a Strongly Driven Quantum Dot".

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