This paper by Handel presents the quantum approach to 1/f noise, published in Physical Review A in 1980. This landmark paper establishes rigorous quantum mechanical foundations for understanding 1/f noise as a fundamental quantum effect arising from infrared divergences in bremsstrahlung processes and radiative corrections to scattering, providing theoretical framework that explains the universal 1/f spectrum observed across diverse physical systems as a consequence of quantum electrodynamics, representing a major advance in fundamental noise theory with broad technological implications.