where ℏ ℏ is the reduced Planck constant. For example, what is the result when the p ^ ^ x operator acts on a quantum state? To find the answer, translate the state by an infinitesimal amount in the x -direction, and calculate the rate that the state is changing, and multiply it by i ℏ ℏ . For example, if a state does not change at all when it is translated in the x -direction, then its x -component of momentum is 0.