We can now describe the occupation of particles on the lattice as a 'ket' of the form | … … , n − − 1 , n 0 , n 1 , … … ⟩ ⟩ . It represents the juxtaposition (or conjunction, or tensor product) of the number states … … , | n − − 1 ⟩ ⟩ | n 0 ⟩ ⟩ , | n 1 ⟩ ⟩ , … … located at the individual sites of the lattice. Recall that