In QFT, elementary particles are described as excitations of underlying fields, with each particle being the excitation of a corresponding field.
My question is, can these fields be artificially excited, such that an experimenter would be able to "create" any number of elementary particles needed, or do these excitations only happen naturally?
You can "artificially" create excitations of a quantum field in your own home. Just flip on a light bulb and you will generate trillions of excitations in the photon field.
Lasers are a little more controlled excitations of the photon field.
Cathode ray tubes (old tvs) generate beams of electrons that could be considered to be excitations in the electron field, but in that case it's more moving electrons that already exist rather than generating new electrons (from other fields) for control.
In particles accelerators such as the LHC experimenters smash excitation of various quantum fields together and their energy collides and interacts and different quantum fields are excited. But as far as I understand it the process is pretty mess and not well controlled.
Maybe in the future we'll have more precise control over more exotic quantum fields. Maybe we'll have Quark bulbs and Higgs lasers.
It first needs to be clear what you understand by "artificially" and "naturally". The LCH (as well as others particles accelerators) creates the conditions to produce particles (and antiparticles) by collisions of high-energy particles. Is that artificial or natural? In theoretical physics, is not common to think with those categories. At the end, you're always finding a description of all possible processes you can find in nature (or reproduce in the laboratory). If you are thinking about "manipulating" a quantum field or something like that, then no, at least in my opinion. Quantum fields are, in the end, theoretical descriptions that humans have created. In the actual theory, they don't have a direct physical realism, like the energy (or, in general, the observables), but are part of a mathematical structure. In some QFT descriptions, they are operators, in others, distributions, in others, local excitations, etc. They just allow you to understand those processes related to particles creation/annihilation. If by artificial you mean to artificially array some conditions to produce particles, then yes, and that's actually what is made in particles accelerators. But in that way of thinking, all laboratory conditions are artificials (which is not actually wrong but not also opposed to nature).
