phononplus

◼ phononplus[Nph] returns the phonon raising operator in the bra-ket representation. Nph is the phonon number cutoff.
◼ phononminus[Nph] returns the phonon lowering operator in the bra-ket representation.

◼ See also: phononnumber, transformQStoPH.

Further examples

Load sneg.

<< sneg`sneg`;

Phonon creation and phonon annihilation operators

ap = phononplus[10]
a = phononminus[10]

Phonon displacement operator and its powers

displ = a + ap
pow[displ, 2] // Expand
pow[displ, 3] // Expand
pow[displ, 4] // Expand