27 research outputs found
Pb10−xCux(PO4)6O: a Mott or charge transfer insulator in need of further doping for (super)conductivity
We briefly review the status quo of research on the putative superconductor Pb9Cu(PO4)6O also known as LK-99. Further, we provide ab initio derived tight-binding parameters for a two- and five-band model, and solve these in dynamical-mean-field theory. The interaction-to-bandwidth ratio makes LK-99 a Mott or charge transfer insulator. Electron or hole doping (which is different from substituting Pb by Cu and thus differs from LK-99) is required to make it metallic and potentially superconducting
Multi-scale space-time ansatz for correlation functions of quantum systems
Correlation functions of quantum systems are central objects in quantum field
theories which may be defined in high-dimensional space-time domains. The
numerical treatment of these objects suffers from the curse of dimensionality,
which hinders the application of sophisticated many-body theories to
interesting problems. Here, we propose a quantum-inspired Multi-Scale
Space-Time Ansatz (MSSTA) for correlation functions of quantum systems. The
space-time dependence is mapped to auxiliary qubit degrees of freedom
describing exponentially different length scales, and the ansatz assumes a
separation of length scales. We numerically verify the ansatz for various
equilibrium and nonequilibrium systems and demonstrate compression rates of
several orders of magnitude for challenging cases. Essential building blocks of
diagrammatic equations, such as convolutions or Fourier transforms are
formulated in the compressed form. We numerically demonstrate the stability and
efficiency of the proposed methods for the Dyson and Bethe-Salpeter equations.
MSSTA provides a unified framework for implementing efficient computations of
quantum field theories.Comment: 25 pages, 26 figure