In the first part of my talk, I will talk about recent experiments on quantum interference.

Distinguishability and mixedness are two fundamental properties of quantum states. They can influence the interference of multiple particles in very different ways. This leads to effects that cannot be observed in the interference of just two particles alone. We demonstrate those effects experimentally by interfering three independent photons in pure or mixed states and observing their behavior in different settings. 

Besides its fundamental relevance, photon interference has important implications for optical quantum technologies. In particular, interference of multiple particles leads to interesting quantum states that can serve as a basis for applications in quantum communication and computing. 

In the second part of my talk, I will talk on how such states can be used in quantum networks. I will then report on recent results, showing how multipartite entangled states realize a secure key exchange in a quantum network with multiple parties. Here, multipartite entanglement has an advantage beyond the security: it enables the communicating parties to stay anonymous.