any theory in which fields are treated by the methods of quantum mechanics; each field can then be regarded as consisting of particles of a particular kind, which may be created and annihilated.
The application of quantum mechanics to physical systems described by fields, such as electromagnetic fields. Quantum field theory was developed to overcome certain deficiencies in Schrödinger's equation, in particular the fact that it was not consistent with special relativity and was difficult to apply to systems involving many particles or to the creation and destruction of particles. See also quantum chromodynamicsquantum electrodynamics.
