  Temporal metamaterials empower novel forms of wave manipulation with direct
applications to quantum state transformations. In this work, we investigate
vacuum amplification effects in anisotropic temporal boundaries. Our results
theoretically demonstrate that the anisotropy of the temporal boundary provides
control over the angular distribution of the generated photons. We analyze
several single and multi-layered configurations of anisotropic temporal
boundaries, each with a distinct vacuum amplification effect. Examples include
the inhibition of photon production along specific directions, resonant and
directive vacuum amplification, the generation of angular and frequency photon
combs, and fast angular variations between inhibition and resonant photon
production.
