👉 In the context of quantum mechanics, a "lag-operator" is an operator that can be interpreted as describing the behavior of a system in time. A lagoperator is described by its eigenvalues and eigenvectors, which represent the properties of the system at different times. In other words, a lagoperator describes how the state of the system changes over time. The concept of a lag-operator was introduced by physicists such as J.J. Sakurai and C.W. Anderson in their seminal work "
