Cellular automata are computational models that use basic rules and techniques to simulate complex phenomena. However, when using conventional computers, these principles are only encapsulated at the software level.
Modern digital electronic computers based on the von Neumann architecture have extremely high hardware complexity. They consist of billions of transistors that are hierarchically and highly structured.
Conventional silicon transistors can only get so small due to problems in manufacturing devices that are only a few dozen atoms wide in certain situations. As a result, researchers have started exploring computing technologies not based on silicon transistors, such as quantum computers.
Alireza Marandi, assistant professor of electrical engineering and applied physics at Caltech, has developed optical hardware to realize cellular automata, a type of computer model consisting of a “world” (a gridded area) containing “cells” (each square of the grid) contains. that can live, die, reproduce and develop into multicellular organisms with their different behaviors. These automata were used to perform computing tasks and Marandi believes they are well suited to photonic technology.
Photonic computing, which uses light instead of electricity, is another area of research, similar to how fiber optic connections have replaced copper wires in computer networks.
Alireza Marandi said: “If you compare an optical fiber with a copper cable, you can transmit information much faster with an optical fiber; The big question is: Can we use the information capacity of light for data processing and not just for communication? To answer this question, we are particularly interested in thinking about unconventional computing hardware architectures that are better suited to photonics than to digital electronics.”
Understanding cellular automata and how they work is important to understand the hardware that Marandi’s team has fully developed. Simulated cells, so-called cellular automata, follow a very simple set of laws. The Game of Life, one of the most famous cellular automata, was developed in 1970 by the English mathematician John Conway.
There are four rules:
1) Any live cell with fewer than two live neighbors dies.
2) Any live cell with more than three live neighbors dies.
3) Any cell with two or three neighbors survives the next generation.
4) Any dead cell with exactly three living neighbors is brought to life.
These rules are applied to the universe in which the cells reside by having a computer play the game of life repeatedly, each repetition representing a generation. These basic principles cause the cells to arrange themselves into complicated structures over the course of a few generations, giving rise to names such as loaf, hive, toad, and heavy spacecraft.
Researchers interested in the theory of mathematics and computer science are drawn to cellular automata like The Game of Life. However, they can also be used in real scenarios. While some basic cellular automata are as computationally powerful as traditional computing systems, others can be used for random number generation, physical simulations, and cryptography.
Others are theoretically as powerful as traditional computer designs. These task-oriented cellular automata resemble an ant colony in that the small activities of individual ants combine into larger collective actions, such as digging tunnels or collecting food and returning it to the nest.
More complex cellular automata with more complicated rules can be used for computational applications such as image object recognition.
He said, “While we are intrigued by the type of complex behaviors that we can simulate with relatively simple photonic hardware, we are excited by the potential of more advanced photonic cellular automata for practical computing applications.”
The researcher explains that cellular automata are well suited for photonic computing because information processing occurs at an extremely low level, eliminating much of the equipment that complicates photonic computing. Cellular automata can operate extremely fast due to the wide bandwidth of photonic computing.
In traditional computing, cellular automata are designed in a computer language based on another “machine” language layer. The cellular automaton cells of Marandi’s photonic computing device are just ultra-short pulses of light, enabling operation up to three orders of magnitude faster than the fastest digital computers.
The researcher said: “The ultra-fast nature of photonic operations and the possibility of on-chip realization of photonic cellular automata could lead to next-generation computers that can perform important tasks much more efficiently than digital electronic computers.”
The US Army Research Office, the Air Force Office of Scientific Research and the National Science Foundation funded the study.
Li, GH, Leefmans, CR, et al. Photonic elementary cellular automata for simulating complex phenomena. Light: science and applications. DOI: 10.1038/s41377-023-01180-9