Artificial Life on Single-Electron Circuits

A promising area of research in nanoelectronics is the development of electrical systems that imitate the dynamics of life. To proceed toward this goal, I have proposed CMOS and single-electron devices that imitates the behavior of neural networks and a reaction-diffusion system, which is a chemical complex system producing dynamic, self-organizing phenomena in the natural world [1], [2]. Constructing an electrical analog of biological systems would enables us to generate artificial biodynamics on a LSI chip and develop bio-inspired information processing systems. Here I briefly overview our recent results on the development of single-electron circuits that perform nonclassical computation inspired by biological systems. First, a novel single-electron device for computation of a Voronoi diagram is introduced. Then I present a single-electron neural circuit for a robust synchrony detection among multiple spike inputs. This work has been extended to utilize stochastic resonance between single-electron neurons for possible robust computation on single-electron circuits. Finally, I introduce a novel semiconductor device in which electronic-analogue dendritic trees grow on multi-layer single-electron circuits, for emulating dendritic computation of neural networks on semiconductor devices. I plan for a semiconductor artificial life (brain) that might be overambitious – but not completely ridiculous. Our final purpose is to uncover new ideas that could help to create better processors or reveal something about the way our brain works. I. A single-electron reaction-diffusion device for computation of a Voronoi diagram Computation of a Voronoi diagram (VD) is one of the typical problems in computer science, and VDs are used in graphics, statistics, geography and economics [3] and [4]. The key feature of VD construction is a partition of twoor three-dimensional space on a sphere of influences generated from a given set of objects, points, or arbitrary geometrical shapes. Here I introduce a novel single-electron device for computation of a VD. A cellular-automaton model of VD formation [5] is used to construct the device that consists of three layers of a 2-D array of single-electron oscillators. A. Single-Electron Circuits for computation of Voronoi Diagram For VD computation, I propose to use single-electron reaction-diffusion (SE-RD) devices. The original SE-RD device consists of arrayed single-electron oscillators and can imitate the operation of chemical RD systems [6]. Figure 1 illustrates the original SE-RD device. The main component is a singleelectron oscillator that consists of a tunneling junction Cj and a high resistance R connected in series at a node and biased by a positive voltage Vdd or a negative one −Vdd. It has voltage Vnode of the node, and Vnode shows the excitatory oscillation that is indispensable for imitating RD systems [6]. To compute a VD with RD systems, spatially localized waves that travel upon computing media at a constant speed are necessary [5], [7]; i.e., the wave-fronts must be smooth and their speed must be constant. The original SE-RD device can generate nonlinear voltage waves. However, the device was not suitable for computing a VD because the wave-fronts were not smooth, as shown in Fig. 2, and their speeds were not constant. The tunneling probability of each electron tunneling at the os+Vdd