As if we didn't have enough noise in our lives, scientists at the Weizmann Institute of Science discovered a new type of noise that poses another challenge to those who love peace and orderly information
It's a story that begins about a hundred years ago, when the physicist Walter Schottky explained the principle of operation of a vacuum tube, in which a current of electrons passes between two contacts (electrodes) separated by a vacuum. In these studies, Schottky discovered an electronic noise that results from the particle nature of the electrons, and from the fact that their flow is not uniform: when an electric voltage is applied between the contacts in the vacuum tube, only some of the electrons manage to pass from contact to contact, while some are pushed back. This non-uniformity creates a kind of "gaps" between the flowing electrons, a phenomenon that generates noise that interferes with the flow of information in the system. This noise is called "whip noise" and is significant in electrical conductors and electronic devices (transistors, diodes, etc.) on the order of nanometers. Whip noise becomes more significant as electronic devices are miniaturized (as happens, for example, in the computer industry).
About a decade after Schottky's discovery, it became clear that in electronic systems there is another type of noise, which results from random fluctuations of the electrons, the intensity of which depends on the temperature. This thermal noise occurs in all electronic systems, both large and small. From then until today, electronic system designers knew that they had to deal with these two types of noise.
In an article published in the scientific journal Nature, Prof. Oren Tal and the members of his research group in the Institute's Department of Chemical and Biological Physics recently reported that they discovered that in electronic systems there is an additional noise, the third in number, resulting from thermal imbalance (temperature differences) in the system. The result is similar to the whip noise discovered by Schottky, except that it is not created as a result of applying voltage, and has a thermal origin. The research was carried out in a system built as a molecular junction based on a hydrogen molecule hanging as a sort of bridge between two electronic contacts. It is, in fact, the smallest electronic device that can be built today.
Prof. Tal says that the discovery of the new noise may make it possible to measure temperature differences in different parts of tiny systems, on the order of nanometers without the need for tiny temperature gauges. This ability is important for research on efficient conversion of heat to electricity using nanometric structures, for the development of tiny quantum engines or for research on efficient heat dissipation in nanometric electronic devices used in the miniaturization of computer systems and electronic systems in general.
The new discovery is also important for the microelectronics industry in another context: in electronic circuits temperature differences often develop in an unplanned manner. Therefore, the noise that was discovered is expected to be generated in these circuits and may even become more significant with the advancement of miniaturization. Until now, the engineers were not aware of this noise, but the discovery of the new "enemy" will allow them to deal with this phenomenon in an intelligent way, for example, through a design that focuses on reducing temperature differences in electronic circuits.
