Local measures of dynamical quantum phase transitions

The authors introduce two types of local effective free energies to detect dynamical quantum phase transitions, which are a useful concept to classify nonequilibrium states of quantum matter. These local effective free energies can be employed in position or momentum space, making them ideal for various measurement techniques in modern quantum simulation platforms. The local effective free energies also allow extraction of truly out-of-equilibrium critical exponents, giving a glimpse into possible out-of-equilibrium quantum universality classes.