# Heidelberg 2015 – wissenschaftliches Programm

## Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

# Q: Fachverband Quantenoptik und Photonik

## Q 18: Quantum Information: Concepts and Methods III

### Q 18.5: Vortrag

### Dienstag, 24. März 2015, 12:00–12:15, K/HS1

**Orbital optimization in fermionic tensor network states** — •Christian Krumnow^{1}, Örs Legeza^{2}, Reinhold Schneider^{3}, and Jens Eisert^{1} — ^{1}Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, Berlin, Germany — ^{2}Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest, Hungary — ^{3}Institute for Mathematics, Technische Universität Berlin, Berlin, Germany

Simulating strongly correlated non-local fermionic models is one of the major task of modern theoretical and computational physics and chemistry. In the presence of strong correlations, calculating ground states using traditional ab-initio methods from quantum chemistry, such as CI and CC, becomes infeasible in certain instances. In these cases tensor-network methods provide a new way forward. The long-range nature of the interaction of such systems, however, renders their straightforward numerical simulation using tensor-network methods difficult and implies new questions concerning the optimal topology and basis used to construct the tensor-network. By combining tensor-networks states (TNS) and suited Gaussian transformations we introduce a scheme which allows to optimise both, the tensor network and its basis using local updates. The TNS allows to approximate even strongly correlated states while the Gaussian transformations encode long range entanglement which cannot be captured by TNS efficiently. The resulting method provides a black box tool which optimises the basis of a general long-range interacting system for approximating the ground state by a TNS as efficient as possible.