Then you should check out our latest publictaion in Nature Photonics here.
In our study we show that multi-photon states behave quite different to classical laser fields, also when it comes to a well-known fundamental feature of light, the so-called Gouy phase. This phenomenon describes the anomalous behavior of light when going through a focus and has not been investigated from a quantum perspective despite its fundamental importance. You can also find a bit more details in our press release here.
Congrats to all co-authors and in particular Markus for the nice work!