Why does a photonic quantum computer require photons? Why wouldn't wave packets work just as well, better in fact since it would get away from the use of fragile single photons? (Article)
When using quantum optics for quantum computation, you can use also wave packets and not just single photons. There is a whole field of continuous-variable (CV) quantum computing that deals with this problem. There are both pros and cons to this approach compared to using single photons:
Entanglement in CV quantum optics can be generated deterministically using optical parametric amplifiers.
Working with Gaussian wave packets is rather simple both in terms of theoretical description and experimental realization.
Gaussian states are not strictly orthogonal so that working with binary data will have a nonzero error rate.
Computations with Gaussian states can be efficiently simulated using classical computers. This means that some non-Gaussian operation is required and these are usually quite demanding experimentally.