Caulfield, H.J., Zavalin, A. & Qian, L. J Supercomput (2012) 62: 681. doi:10.1007/s11227-011-0583-7
The thermodynamic “permission” to build a device that can evaluate a sequence of logic operations that operate at zero energy has existed and has been unsolved for about 40 years. Over the last four years, we have explored the possibility of a constructive proof. And we finally have found successfully such a proof and found that lossless logic systems could actually be built. It can only be implemented by optics. In this paper, the problems addressed are speed, size, and error rate. The speed problem simply vanishes, as it was an inference from the implicit assumption that the logic would be electronic. But the other two problems are real and must be addressed if energy-free logic is to have any significant applications. Initial steps in solving the size and error rate are addressed in more detail.