Shrinkage-induced cracking, commonly observed in nature, produces polygonal crack patterns in environments like drying lake beds, permafrost, and cooling lava flows. These patterns can be reproduced in the lab by desiccating dense suspensions on rigid substrates, where shrinkage stresses lead to cracking. Due to its technological potential, we explore the controlled generation of crack patterns by introducing anisotropic mechanical properties into dense pastes before desiccation, using a discrete element model to study the evolution of these patterns as materials shrink. Our simulations reveal how anisotropy influences crack structure and fragment shapes, highlighting also those features that remain robust regardless of the strength of anisotropy. Additionally, we explain how inherent material disorder causes cracking of the layer to occur in bursts following scale free statistics with non-universal exponents.

We discuss quantum network Bell nonlocality in a setting where the network structure is not fully known. More concretely, an honest user may trust their local network topology, but not the structure of the rest of the network, involving distant (and potentially dishonest) parties. We demonstrate that quantum network nonlocality can still be demonstrated in such a setting, hence exhibiting topological robustness. Specifically, we present quantum distributions obtained from a simple network that cannot be reproduced by classical models, even when the latter are based on more powerful networks. In particular, we show that in a large ring network, the knowledge of only a small part of the network structure (involving only 2 or 3 neighbouring parties) is enough to guarantee nonlocality over the entire network. This shows that quantum network nonlocality can be extremely robust to changes in the network topology. Moreover, we demonstrate that applications of quantum nonlocality, such as the black-box certification of randomness and entanglement, are also possible in such a setting.

https://arxiv.org/abs/2406.09510, https://doi.org/10.1103/PhysRevLett.134.010202 

Recent breakthroughs in the development of digital quantum devices promise to grant computational capacities far beyond the reach of classical architectures, and open unprecedented possibilities to study quantum many-body systems. This swift progress is fueling intense interest in the complex interplay of unitary quantum dynamics and non-unitary processes arising naturally in experiments, such as dissipation stemming from coupling to the environment or projective measurements performed on the system. This talk illustrates the rich dynamical phase diagrams that can emerge in these non-unitary settings. In the first part, we address the challenges of protecting quantum coherence against environmental noise, and explore the dynamical phase diagram of dissipative quantum many-body systems. In contrast to the general expectation that in an open system coherent information is quickly lost to the dissipative environment, we construct a regime of open quantum dynamics, functioning as a quantum error-correcting code which is dynamically protected against generic boundary noise. We comment on the implications of these results for designing robust quantum devices. We then turn to the effects of local measurements performed on the system. Specifically, we demonstrate that appropriately chosen projective measurements can imprint highly non-trivial order on quantum many-body systems, realizing the out-of-equilibrium counterpart of spontaneous symmetry breaking and symmetry protected topological order.