The paper “Morphing supermodes: a full characterization for enabling multimode quantum optics” by DYSCO group is published in Physical Review Letters
optical systems possessing a high number of degrees of freedom serves as platform for several applications in quantum information and communication. The characterization of their properties is based on the identification of the so called supermodes, that are a coherent superposition of the original modes of the systems and that allow to decouple the system dynamics in terms of statistically independent squeezed states. Supermodes enable an optimal generation, manipulation and detection of the non-classical information. For example they allow to generate, on demand, tailored quantum states such as "cluster states" in the frequency comb of a synchronously pumped optical parametric oscillator (SPOPO). The ongoing development of new devices and platforms for quantum optics is enlarging the range of situations requiring a multimode dynamics-decoupling treatment. This work shows that the supermodes formalism is not sufficient for characterising these systems in terms of statistically independent physical observables, and one have to adopt a most general strategy that leads to novel entities that have been called "morphing supermodes". These modes change their shape during the system dynamic evolution and they allow the study of a large variety of key resources for the quantum optics such as, for example, silicium microring resonators or optomechanical devices.