Debasish Banerjee with Arnab Sen (IACS) have discussed on Quantum Scars from Zero Modes in an Abelian Lattice Gauge Theory on Ladders in Physical Review Letters 126, 220601 (2021).

A hallmark of naturally occurring quantum many-body systems around us is the flow back to equilibrium when disturbed. This accounts for the overwhelming success of statistical mechanics in describing  complex systems. For quantum systems, one attempts to formalize this observation through the  Eigenstate Thermalization Hypothesis (ETH). ETH states that the measurement of a local operator on individual eigenstates of a quantum system with many degrees of freedom yields a thermal distribution, with the temperature determined by the energy density of the eigenstate.

So universally is this observed for normal quantum systems, that any deviation  from this behaviour attracts notice and challenges us to understand the mechanisms which evade the ETH. In this article, demonstrate a new mechanism which gives rise to energy eigenstates that violate the ETH and display anomalous thermalization, if the initial starting state has a large overlap with the  special "quantum scar" states. The formation of the quantum scars is due to the pseudorandom superposition of interacting zero-modes of the "kinetic energy" term of the system. The scars can be practically realized by switching on  an additional "potential-energy" operator, which causes the necessary superposition. The quantum scars are eigenstates of the complete interacting Hamiltonian with exact integer eigenvalues. This is an exceedingly novel phenomenon  for strongly interacting many-body quantum systems.

Here is the link.