Fock state
A quantum sate with a definite number of non-interacting identical particles.

Wigner function of a Fock state with photon number n=2 (Author: Geek3, created with Mathematica).
A quantum sate with a definite number of non-interacting identical particles.
Wigner function of a Fock state with photon number n=2 (Author: Geek3, created with Mathematica).