In Chapter 4 of his recent book *Quanta and Fields*, Sean Carroll uses a scalar free field to show how particles seem to emerge from field quantization. 

On P.94, he talks about combining field modes with different wave numbers but all in their first excited (one particle) states to make a wave packet. He then writes:

*What we're seeing is that a quantum state constructed from a superposition of free-field modes in their first excited states looks and acts like the wave function of a single particle of mass m.*

Isn't the wave packet constructed by adding field modes just a field configuration for which you could compute an amplitude? Then I don't see how it could **act** like the wave function of a particle.