The world of computing is in transition. As chips become smaller and faster, they dissipate more heat, which is energy that is entirely wasted. By some estimates the difference between the amount of energy required to carry out a computation and the amount that today's computers actually use, is some eight orders of magnitude. Clearly, there is room for improvement. One of the outside runners in the race to take the world of logic by storm is reversible computing. By that, computer scientists mean computation that takes place in steps that are time reversible. These requirements for reversibility place tight constraints on the types of physical systems that can do this kind of work, not to mention on their design and manufacture. Ordinary computer chips do not qualify--their logic gates are not reversible and they also suffer from another problem. When conventional logic gates produce several outputs, some of these are not used and the energy required to generate them is simply lost. These are known as garbage states. Himanshu Thapliyal and Nagarajan Ranganathan at the University of South Florida propose a new way of detecting errors in computations and say that their method is ideally applicable to reversible computing and, what's more, naturally reduces the number of garbage states that a computation produces. If a reversible computation produces a series of outputs, then the inverse computation on these outputs should reproduce the original states. So their idea is to perform the inverse computation on the output states and if this reproduces the original states, then the computation is error free. And because this relies on reversible logic steps, it naturally minimizes the amount of garbage states that are produced in between. The beauty of this approach is that it has the potential to be dissipation-free. So not only would it use far less energy than conventional computing, it needn't lose any energy at all. At least in theory. More information can be found here: http://arxiv.org/abs/1101.4222

Eavesdropper

## Comments