Fractonic critical point proximate to a higher-order topological insulator: How UV blend with IR?
Yizhi You, Julian Bibo, Taylor L. Hughes, Frank Pollmann
Abstract
We propose an unconventional topological quantum phase transition connecting a higher-order topological insulator (HOTI) and a featureless Mott insulator sharing the same symmetry patterns. We delineate the effective theory description of the quantum critical point (QCP) by combining the bosonization approach and the coupled-stripe construction of 1D critical spin ladders. The phase transition theory is characterized by a critical dipole liquid theory with subsystem $U(1)$ symmetry whose low energy modes contain a Bose surface along the $k_x,k_y$ axis. Such a quantum critical point manifests fracton dynamics and the breakdown of the area law entanglement entropy due to the existence of a Bose surface. We numerically confirm this finding by measuring the entanglement entropy, topological Berry phase, and the static structure factor throughout the topological transition and compare it with our previous approach obtained from the percolation picture. A significant new element of our phase transition theory is that the infrared (IR) effective theory is controlled by short wave-length fluctuation with peculiar UV-IR mixing.