Tailored light excitation and nonlinear control of lattice vibrations have emerged as powerful strategies to manipulate the properties of quantum materials out of equilibrium. Generalizing the use of coherent phonon-phonon interactions to nonlinear couplings among other types of collective modes would open unprecedented opportunities in the design of novel dynamic functionalities in solids. For example, the collective excitations of magnetic order –magnons– can carry quantum information with little energy dissipation, and their coherent and nonlinear control would provide an attractive route to achieve collective-mode-based information processing and storage in forthcoming spintronics and quantum information science.

In this talk, I will show that intense terahertz (THz) fields can initiate processes of magnon up-conversion and magnon mixing mediated by an intermediate magnetic resonance. By using a suite of advanced spectroscopic tools, including a newly demonstrated two-dimensional THz polarimetry technique, we unveil these anharmonic magnon coupling phenomena in a canted antiferromagnet. These results demonstrate a route to inducing desirable energy transfer pathways between coherent magnons in solids and pave the way for a new era in the development of ultrafast control of magnetism.

Understanding how complex ecological communities function, persist, and adapt is one of the grand challenges of contemporary science. Ecosystems involve interactions among countless organisms, each responding to a constantly changing environment. Yet, despite this apparent complexity, ecological systems often display strikingly regular, robust, and universal patterns.
This talk discusses how tools from statistical physics, complex systems theory, and effective modelling enable us to uncover the emergent properties of ecological communities and to bridge the gap between microscopic dynamics and macroscopic phenomena. The aim of the talk is to convey how a physics perspective can provide unifying principles for ecology, and how theoretical insights, when combined with data, can deepen our understanding on diversity and dynamics of ecological systems.

We will speculate on the novel concept of mereological quantum phase transition (m-QPTs). Our framework is based on generalized tensor product structures (g-TPS), a parameter-dependent Hamiltonian, and a quantum scrambling functional. By minimizing the scrambling functional, one selects a g-TPS, enabling a pullback of the natural information-geometric metric on the g-TPS manifold to the parameter space. The singularities of this induced metric in the thermodynamic limit characterize the m-QPTs. We will illustrate this framework through analytical examples involving quantum coherence and operator entanglement Ref: https://arxiv.org/abs/2510.06389 <https://arxiv.org/abs/2510.06389>