AFRL Funds Superfast Secure Computing Published Nov. 2, 2009 By Maria Callier Office of Scientific Research ARLINGTON, Virginia -- Air Force Research Laboratory-funded physicists at the University of Michigan are developing innovative components for quantum, or superfast, computers that will improve the security of storing and transmitting data on Air Force systems. This work is significant amid considerable concern regarding the use of semiconductors--which, despite remarkable suitability for modern electronics and photonics, would be insufficient for quantum computing if they precipitate coherence loss in the electron spin. At the helm of UM's lab-sponsored effort is Professor Duncan Steel, whose team began investigations that--thanks to assistance from Naval Research Laboratory collaborators--ultimately produced a means to create, maintain, control, and measure quantum coherence optically, via a single electron and hole, in a quantum dot structure. The feat of sustaining a constant electrical charge for an extended time period in a solid-state nanostructure (such as a quantum dot) is likely key to the technology's long-term success. Accordingly, the physicists' subsequent challenge has been in manipulating the continuous electrical charge to perform basic computing tasks. In this phase of research, Dr. Steel and his cohort are focused on "spin and phase"--quantum properties of the electron and hole that can be used to transport and store information. By demonstrating well-defined spin and phase, the researchers have been better able to control and maintain information. Building upon this conceptual model, the UM team has since advanced to the more complex applications needed for quantum computing, using several related technologies (the state-of-the-art frequency, stabilized lasers, and advanced laser control system) also developed with AFRL support to enable reliable, ongoing optical control. In the process, Dr. Steel's team--a membership that includes Dr. L. J. Sham (University of California at San Diego), another researcher to have previously received lab funding--has itself furthered the understanding of optical control. Having gained new knowledge of how spin-and-phase information is lost and how that loss can be reduced, the researchers have been able to demonstrate increased quantum storage time. With the use of ultrafast laser technology, this increase will accommodate upwards of a million quantum operations before information is lost. Dr. Steel's research also receives funding support from the Army Research Office, National Science Foundation, Office of Naval Research, Intelligence Advanced Research Projects Activity's Laboratory for Physical Sciences, and Defense Advanced Research Projects Agency. Its immediate importance notwithstanding, the long-term goal of this basic research is to push the frontier of modern electronics and optics into the realm of quantum behavior, where more complex computing problems can be solved at increasingly faster speeds.