PAPER: Quantum statistical physics, condensed matter, integrable systems Quantifying stability of quantum statistical ensembles

摘要

We investigate different measures of stability of quantum statistical ensembles with respect to local measurements. We call a quantum statistical ensemble ‘stable’ if a small number of local measurements cannot significantly modify the total-energy distribution representing the ensemble. First, we numerically calculate the evolution of the stability measure introduced in our previous work Hahn and Fine (2016 Phys. Rev. E 94 062106) for an ensemble representing a mixture of two canonical ensembles with very different temperatures in a periodic chain of interacting spins-1/2. Second, we propose other possible stability measures and discuss their advantages and disadvantages. We also show that, for small system sizes available to numerical simulations of local measurements, finite-size effects are rather pronounced.