Fock state

In quantum mechanics, a Fock state or number state is a quantum state that is an element of a Fock space with a well-defined number of particles (or quanta). These states are named after the Soviet physicist Vladimir Fock. Fock states play an important role in the second quantization formulation of quantum mechanics. Therefore, it is clear that adjoint of Creation (Annihilation) operator doesn't go into itself. Hence, they are not Hermitian operators.Wigner function of | 0 ⟩ {displaystyle |0 angle } Wigner function of | 1 ⟩ {displaystyle |1 angle } Wigner function of | 2 ⟩ {displaystyle |2 angle } Wigner function of | 3 ⟩ {displaystyle |3 angle } Wigner function of | 4 ⟩ {displaystyle |4 angle } In quantum mechanics, a Fock state or number state is a quantum state that is an element of a Fock space with a well-defined number of particles (or quanta). These states are named after the Soviet physicist Vladimir Fock. Fock states play an important role in the second quantization formulation of quantum mechanics. The particle representation was first treated in detail by Paul Dirac for bosons and by Pascual Jordan and Eugene Wigner for fermions. :35 One specifies a multiparticle state of N non-interacting identical particles by writing the state as a sum of tensor products of N one-particle states. The tensor products must be alternating products or symmetric products of the underlying one-particle Hilbert space according to whether the particles are fermions or bosons. If the number of particles is variable, one constructs Fock space as the direct sum of the tensor product Hilbert spaces for each particle number.