Speaker
Description
Highly-excited states of quantum many-body systems are typically described well by the eigenstate thermalization hypothesis and show volume law entanglement entropy. In models with quantum many-body scars, however, a few states at high energies behave differently. These scar states typically have area law entanglement entropy and form a tower of states with equidistant energies. The scar states thus violate the eigenstate thermalization hypothesis, and they can give rise to revival dynamics. One can also see quantum many-body scars as a way to have several ground-state-like energy eigenstates in a single system, which opens new opportunities for quantum engineering. Here, we discuss to what extent scar states are like ground states. In particular, we show that scar states can undergo phase transitions like ground states and that adiabatic time evolution is possible for scar states. We also propose and construct inverted quantum many-body scars. These are systems, in which most of the states in the spectrum are localized and have area law entanglement entropy, while a few, highly-excited states have much higher entanglement entropy.
