ABSTRACT
The properties of a quantum mechanical system composed of many identical particles are most conveniently described in terms of the second-quantized, Heisenberg representation, particle-creation, and annihilation operators. The creation operator, ψ†(r, t), when acting to the right on a state of the system, adds a particle to the state at the space-time point r, t; the annihilation operator ψ(r, t), the adjoint of the creation operator, acting to the right, removes a particle from the state at the point r, t.
