Perspective on electromagnetically induced transparency vs Autler–Townes splitting

Electromagnetically induced transparency and Autler–Townes splitting are two distinct yet related effects. These phenomena are relevant to quantum technologies, including quantum memory, quantum switching, and quantum transduction. Here, the similarities and differences between these phenomena along historical and conceptual lines are discussed and their realizations on various physical platforms including atomic gases, superconducting circuits, and optomechanics are elaborated. In particular, the author clarifies two approaches to assessing which phenomenon is observed based on a black-box approach of modeling the output, given a particular input vs analyzing the underpinning physics. Furthermore, the author highlights the ability to effect a continuous transition between the two seemingly disparate phenomena.