👉 Underfired is a concept in quantum mechanics, which refers to the state of a particle that is not fully populated or excited enough. In other words, it represents the minimum level of energy required for a system to be observed as being "up" (or "active"). This term is often used in discussions about quantum entanglement and superposition, where particles are said to be underfired if they are not fully occupied by another particle or when they have been measured.