The precise quantum control of single photons, together with the intrinsic advantage of being mobile make optical quantum system ideally suited for quantum information applications that require communication or the delegation of tasks. Prominent examples include quantum cryptography as well as quantum clouds and quantum computer networks.
Here I present the current architectures for scalable photonic quantum computers and special purpose applications that exploit advantages of photonic quantum system. This is shown by examples for various quantum computations such as quantum machine learning and in particular reinforcement learning, in addition to secure quantum and classical computing tasks that require quantum networks. As outlook I will discuss technological challenges for the scale up of photonic quantum computers and remarkable opportunities for special-purpose applications such as neuromorphic circuits.