Subdimensional criticality: Condensation of lineons and planons in the X-cube model

We study quantum phase transitions out of the fracton ordered phase of the Z(N) X-cube model. These phase transitions occur when various types of subdimensional excitations and their composites are condensed. The condensed phases are either trivial paramagnets, or are built from stacks of D = 2 or 3 deconfined gauge theories, where D is the spatial dimension. The nature of the phase transitions depends on the excitations being condensed. Upon condensing dipolar bound states of fractons or lineons, for N >= 4 we find stable critical points described by decoupled stacks of D = 2 conformal field theories. Upon condensing lineon excitations, when N > 4 we find a gapless phase intermediate between the X-cube and condensed phases, described as an array of D = 1 conformal field theories. In all these cases, effective subsystem symmetries arise from the mobility constraints on the excitations of the X-cube phase and play an important role in the analysis of the phase transitions.

Automated summary

In this study, we investigate quantum phase transitions occurring outside of the fracton ordered phase of the Z(N) X-cube model. These phase transitions are characterized by the condensation of subdimensional excitations and their composites, resulting in either trivial paramagnets or stacks of D = 2 or 3 deconfined gauge theories. The nature of these transitions depends on the type of excitations being condensed, leading to stable critical points or gapless intermediate phases. Effective subsystem symmetries arising from mobility constraints on X-cube phase excitations play a crucial role in analyzing the phase transitions.