Weak Ergodicity Breaking and Quantum Many-Body Scars in Spin-1 XY Magnets

Weak-ergodicity Breaking in Mean-field Spin-glass Models

Classical and Quantum Chiral Order in Frustrated XY Magnets

Recent studies on the chiral order of regularly frustrated XY magnets are reviewed both in classical and quantum cases. In the classical case, chiral transition is a thermal one, while in the quantum case, it is a quantum phase transition. Importance of spatial dimensionality on the chiral order is clarified. Particular attention is paid to the possible “spin-chirality decoupling” phenomenon, a...

Self-sustained clusters and ergodicity breaking in spin models.

Self-sustained spin clusters are analytically linked to ergodicity breaking in fully connected Ising and Sherrington-Kirkpatick (SK) models, relating the less understood spin space to the well understood state space. This correspondence is established through the absence of clusters in the paramagnetic phase, the presence of one dominant cluster in the Ising ferromagnet, and the formation of no...

Quantum ergodicity for Pauli Hamiltonians with spin 1/2

Quantum ergodicity, which expresses the semiclassical convergence of almost all expectation values of observables in eigenstates of the quantum Hamiltonian to the corresponding classical microcanonical average, is proven for non-relativistic quantum particles with spin 1/2. It is shown that quantum ergodicity holds, if a suitable combination of the classical translational dynamics and the spin ...

Distribution of time-averaged observables for weak ergodicity breaking.

We find a general formula for the distribution of time-averaged observables for systems modeled according to the subdiffusive continuous time random walk. For Gaussian random walks coupled to a thermal bath we recover ergodicity and Boltzmann's statistics, while for the anomalous subdiffusive case a weakly nonergodic statistical mechanical framework is constructed, which is based on Lévy's gene...