New quantum mechanical methods in spectral analysis offer significant advantages, including enhanced resolution and more comprehensive analysis of individual spectral peaks. This book describes the novel applications of these methods to signal processing across a wide range of interdisciplinary research fields. These methods allow researchers to evaluate data with an accuracy that is not possible with conventional methods. Focusing on applications in various areas of physics, such as accelerator physics and fusion physics radiation oncology, the text critically compares new and established methodologies based on a detailed analysis of experimental results obtained from each method.