Anomalous low-frequency conductivity in easy-plane XXZ spin chains
Utkarsh Agrawal, Sarang Gopalakrishnan, Romain Vasseur, Brayden Ware
Abstract
Computing the conductivity of interacting systems at nonzero temperature is a fundamental challenge. In integrable systems, the framework of generalized hydrodynamics lets one access the dc limit. Here, the authors combine generalized hydrodynamics with sum rules and locality to compute the ac conductivity of the XXZ spin chain (or, equivalently, interacting spinless fermions). Generically, it diverges at low frequencies, but for special ``commensurate'' parameters it has a finite limit. These results explain longstanding puzzles regarding the discontinuous parameter dependence of the dc response.
Topics & Concepts
Integrable systemFermionLimit (mathematics)Spin (aerodynamics)PhysicsConductivityPlane (geometry)Condensed matter physicsChain (unit)LocalityQuantum mechanicsStatistical physicsMathematical physicsMathematical analysisMathematicsThermodynamicsPhilosophyGeometryLinguisticsQuantum many-body systemsTensor decomposition and applicationsAlgebraic structures and combinatorial models