20.500.12556/RUL-165854 Normal weak eigenstate thermalization Eigenstate thermalization has been numerically shown to occur for few-body observables in a wide range of nonintegrable models. For intensive sums of few-body observables, a weaker version of eigenstate thermalization known as weak eigenstate thermalization has been proved to occur in general. Here, we unveil a stricter weak eigenstate thermalization phenomenon that occurs in quadratic models exhibiting quantum chaos in the single-particle sector (quantum-chaotic quadratic models) and in integrable interacting models. In such models, we argue that few-body observables that have a properly defined system-size independent norm are guaranteed to exhibit at least a polynomially vanishing variance (over the entire many-body energy spectrum) of the diagonal matrix elements, a phenomenon we dub normal weak eigenstate thermalization. We prove that normal weak eigenstate thermalization is a consequence of single-particle eigenstate thermalization, i.e., it can be viewed as a manifestation of quantum chaos at the single-particle level. We report numerical evidence of normal weak eigenstate thermalization for quantum-chaotic quadratic models such as the three-dimensional Anderson model in the delocalized regime and the power-law random banded matrix model, as well as for the integrable interacting spin-1/2 XYZ and XXZ models. quantum chaos thermalization localization kvantni kaos termalizacija lokalizacija true false true Angleški jezik Slovenski jezik Članek v reviji 2024-12-12 12:20:38 2024-12-12 12:20:38 2024-12-13 03:57:45 0000-00-00 00:00:00 2024 0 0 Str. 104202-1-104202-19 iss. 10 Vol. 110 2024 0000-00-00 PostprintKoncna Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 538.9 2469-9950 10.1103/PhysRevB.110.104202 217686275 Normal_weak_ETH.pdf Normal_weak_ETH.pdf 1 6FFEFA04AB071A7D934EAD7BAE851970 5604ac544e6a010bbbd99e221f587f6f7de3f46166866df50b60f12813668582 ec63c80a-b87a-11ef-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=197115 https://journals.aps.org/prb/abstract/10.1103/PhysRevB.110.104202 0 f62e5127-b87a-11ef-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=197116 Fakulteta za matematiko in fiziko 0 0 0