Foliated Field Theory and String-Membrane-Net Condensation Picture of Fracton Order

Foliated fracton order is a qualitatively new kind of phase of matter. It is similar to topological order, but with the fundamental difference that a layered structure, referred to as a foliation, plays an essential role and determines the mobility restrictions of the topological excitations. In this work, we introduce a new kind of field theory to describe these phases: a foliated field theory. We also introduce a new lattice model and string-membrane-net condensation picture of these phases, which is analogous to the string-net condensation picture of topological order.Comment: 22+15 pages, 8 figures; v3 added a summary of our model near the end of the introductio

Anomalies and entanglement renormalization

We study 't Hooft anomalies of discrete groups in the framework of (1+1)-dimensional multiscale entanglement renormalization ansatz states on the lattice. Using matrix product operators, general topological restrictions on conformal data are derived. An ansatz class allowing for optimization of MERA with an anomalous symmetry is introduced. We utilize this class to numerically study a family of Hamiltonians with a symmetric critical line. Conformal data is obtained for all irreducible projective representations of each anomalous symmetry twist, corresponding to definite topological sectors. It is numerically demonstrated that this line is a protected gapless phase. Finally, we implement a duality transformation between a pair of critical lines using our subclass of MERA.Comment: 12+18 pages, 6+5 figures, 0+2 tables, v2 published versio

Symmetry-protected adiabatic quantum transistors

The standard circuit model of quantum computation differs in principle from a modern day computer chip in that computation is brought to stationary qubits in the former whereas information is routed spatially across a chip by transistors in the latter. Recently a model was proposed that addresses this key difference in implementation, it was dubbed the adiabatic quantum transistor model to emphasise its similarity to a classical transistor. Here we generalise this model to the setting of spin chains in inherently quantum phases of matter with a property called symmetry-protected order. Our generalisation is significant as it shows the computational properties of the model persist robustly throughout each symmetry-protected quantum phase of matter