Self-consistent projection operator theory for quantum many-body systems

Theory of many-body effects in the Kondo-lattice model: Projection-operator method

The magnetic behaviour of various materials is due to an indirect interaction of localizedmagnetic moments, which is based on itinerant electrons in a conduction band. TheKondo-lattice model is an elegant approach for a quantum-mechanical description of thisprocess. It reduces the relevant physics to an intra-atomic exchange interaction of thelocalized and the itinerant electron...

Hypergeometric resummation of self-consistent sunset diagrams for steady-state electron-boson quantum many-body systems out of equilibrium

Héctor Mera,1,2,* Thomas G. Pedersen,2,3 and Branislav K. Nikolić1 1Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716-2570, USA 2Department of Physics and Nanotechnology, Aalborg University, DK-9220 Aalborg East, Denmark 3Center for Nanostructured Graphene (CNG), DK-9220 Aalborg East, Denmark (Received 20 December 2015; revised manuscript received 21 August 201...

Quantum Many–Body Problems and Perturbation Theory

We show that the existence of algebraic forms of exactly-solvable A−B− C−D and G2, F4 Olshanetsky-Perelomov Hamiltonians allow to develop the algebraic perturbation theory, where corrections are computed by pure algebraic means. A classification of perturbations leading to such a perturbation theory based on representation theory of Lie algebras is given. In particular, this scheme admits an ex...

Nonequilibrium Relativistic Quantum Many-Body Theory

Quantum information in many-body systems

ABSTRACT: Quantum information sheds new light on quantum systems, complementary to the traditional point of view of energy. A key notion is entanglement, which measures quantum correlations within the system. Understanding entanglement of ground states is crucial to efficiently represent such many-body states using a small number of variational parameters. This is but one example of very powerf...