In quantum field theory there are a number of quantum fields, one for each type of particle. I consider just a single field, for example the electromagnetic field, and as a free field. As I understand we can choose 'momentum (or wavevector) and occupancy' as a basis for this field (or any field). Using this basis, let's consider only a single momentum (or wavevector).
This is commonly introduced when explaining quantum field theory as analogous to a quantum harmonic oscillator (as considered in this question). The harmonic oscillator system as a whole has a fixed frequency, corresponding to the frequency of coherent states. However, individual energy states have distinct frequencies. Energy states of the oscillator correspond to occupancy states of the quantum field of a given momentum, so I wanted to check that each of these also has a distinct frequency?