👉 Commutation is a mathematical concept in quantum mechanics, which refers to the operation of transforming one quantum state into another. It involves a transformation of the wavefunction that reverses the phase of the wavefunction at each site. The commutation relation states that if two operators commute (i.e., they satisfy \([\hat{A}, \hat{B}] = [A, B]\)), then their product is zero: \[ [\hat{A} , \hat{B}] = 0