= Fock state
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A <Fock state> has definite <occupation number> in each of a specified set of modes. For <bosonic> modes, $|n_1,n_2,\ldots\rangle$ is constructed from the <Fock vacuum> with normalized products of <creation operators>; <fermionic> <occupation numbers> are zero or one and ordering fixes signs.
A one-<photon> state in one mode is different from a <coherent state> with the same mean <photon> number: the former has sharp number while the latter has number fluctuations. The mode specification matters, because changing basis can turn a fixed occupation pattern into a <superposition> of patterns in the new modes. A <Fock state> therefore gives definite <particle> counts in its chosen modes, not generally definite positions or a classical field amplitude.
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