Effect of dissipation on the one-dimensional Mott transition
Oscar Bouverot-Dupuis (LPTMS, Orsay)
In one-dimensional quantum systems, the Mott transition is a well-understood superfluid-to-insulator transition separating a perfectly conducting Luttinger liquid (LL) from a Mott insulator (MI). In this talk, I will explore how this transition is modified when the system is coupled to local dissipative baths. Using a Caldeira-Leggett description of the environment and bosonization techniques, the problem can be mapped onto an effective (1+1)D field theory with non-Markovian interactions induced by dissipation. As a starting point, I will revisit the dissipation-free case and show how physical insights allow to design efficient Monte Carlo algorithms. These algorithms are then used on the dissipative problem to establish its full phase diagram. This reveals that dissipation qualitatively alters the transition: the direct LL-MI transition is avoided by the appearance of a intermediate dissipation-induced phase.
Observing weakly broken conservation laws in a dipolar Rydberg quantum spin chain
Alice Marché (LPTMS, Orsay)
Integrability, one of the main technical theoretical tools for the analysis of models of physical setups, is not just a mathematical property: it has deep physical consequences. Integrable and non-integrable setups display qualitative different physical behaviours, related to the presence (or absence) of families of extensive conservation laws. In the presence of weak perturbations, a well-known dilemma takes place: is the system akin to a thoroughly non-integrable setup, or does it carry memory that integrability has been only weakly broken? In this theoretical and experimental collaboration we show that the weak breaking of conservation laws leaves a clear experimental fingerprint in a one-dimensional quantum spin chain of as few as 14 Rydberg atoms. Weak integrability breaking from resonant dipole-dipole interactions is directly detectable within experimentally accessible times in the dynamics of non-local observables. In particular, magnetization fluctuations are highly sensitive to the breaking of fragile conservation laws and exhibit anomalous growth, which we observe experimentally; similar signatures appear in a semilocal string observable. We establish Rydberg-atom arrays as a platform to test perturbative descriptions of quantum many-body dynamics with weak integrability breaking. Based on: https://arxiv.org/abs/2602.02251