|physics See also energy level a state of a system characterized by a set of quantum numbers and represented by an eigenfunction. The energy of each state is precise within the limits imposed by the uncertainty principle but may be changed by applying a field of force. States that have the same energy are called degenerate|
A description in quantum mechanics of a physical system or part of a physical system. Different quantum states for a physical system show discrete differences in the value of the variables used to define the state. For example, the spin of an isolated electron can take on one of only two values; there are no other quantum states available for the electron and no intermediate values, since spin is quantized. The quantum state is sometimes described by a set of quantum numbers that pick out the appropriate values for describing the state.