In 2025, we will mark the 100th anniversary of J.B. Johnson’s accidental discovery of 1/f noise in experiments designed to test Schottky’s theory of shot noise in vacuum tubes (f is frequency). Since this first observation, the fluctuation processes, with the spectra close to 1/f dependence, have been observed in physics, technology, biology, astrophysics, geophysics, economics, language, and music. Despite its long history and technological importance, low-frequency noise remains the subject of intense debate. In recent years, 1/f noise attracted attention in the context of quantum computing. In this Lecture, I will give a historical overview of the noise field and describe the fundamental properties of the 1/f noise in semiconductors, metals, and graphene. After that, I will discuss how low-frequency noise can be used as a source of information about materials rather than a nuisance hampering the device’s operation. The specific examples will include noise in charge-density-wave quantum materials, and ultra-wide-band-gap semiconductors. I will show that noise spectroscopy can be utilized for monitoring phase transitions, determining material degradation, and assessing the quality of the materials and device technology.
You can download the brief version of the lecture HERE.