PSEUDOSPIN S=1 FORMALISM AND SKYRMION-LIKE EXCITATIONS IN THE THREE-BODY CONSTRAINED EXTENDED BOSE-HUBBARD MODEL
Moskvin A.S.

Received: February 16, 2015

DOI: 10.7868/S0044451015090126

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We discuss the most prominent and intensively studied S=1 pseudospin formalism for the extended boson Hubbard model (EBHM) with the on-site Hilbert space truncated to the three lowest occupation states n=0, 1, 2. The EBHM Hamiltonian is a paradigmatic model for the highly topical field of ultracold gases in optical lattices. The generalized non-Heisenberg effective pseudospin Hamiltonian does provide a deep link with a boson system and a physically clear description of ``the myriad of phases'', from uniform Mott insulating phases and density waves to two types of superfluids and supersolids. We argue that the 2D pseudospin system is prone to a topological phase separation and focus on several types of unconventional skyrmion-like topological structures in 2D boson systems, which have not been analyzed until now. The structures are characterized by a complicated interplay of insulating and two superfluid phases with a single-boson and two-boson condensation, respectively.