arXiv subjects

G. J. Cruz

Publications and source records attributed to G. J. Cruz.

2 recordsLinked to original sources

arXiv2019

Spinor bosons in optical superlattices: a numerical study

The ground state of spin-1 ultracold bosons trapped in a periodic one-dimensional optical superlattice is studied. The two sites of the unit cell have an energy shift between them, whose competition with the spin-dependent strength is the main focus of this paper. Charge density wave (CDW) phases appear for semi-integer and integer densities, leading to rich phase diagrams with Mott insulator, superfluid and CDW phases. The spin-dependent interaction favors insulator phases for integer densities and disfavors CDW phases for semi-integer densities, which tend to disappear. Also, quantum phase transitions at finite values of the spin-dependent strength were observed. For integer densities, Mott insulator-superfluid-CDW insulator transitions appear for an energy shift lower (higher) than the local repulsion for the global density $ρ=1$ ($ρ=2$).

cond-mat.quant-gas↗

arXiv2019

Phase diagrams of bosonic $AB_{n}$ chains

The $AB_{N-1}$ chain is a system that consists of repeating a unit cell with $N$ sites, where between the $A$ and $B$ sites there is an energy difference of $λ$. We considered bosons in these special lattices and took into account the kinetic energy, the local two-body interaction, and the inhomogenous local energy in the Hamiltonian. We found the charge density wave (CDW) and superfluid and Mott insulator phases, and constructed the phase diagram for $N=2$ and $3$ at the thermodynamic limit. The system exhibited insulator phases for densities $ρ=α/N$, with $α$ being an integer. We obtained that superfluid regions separate the insulator phases for densities larger than one. For any $N$ value, we found that for integer densities $ρ$, the system shows $ρ+1$ insulator phases, a Mott insulator phase, and $ρ$ CDW phases. For non-integer densities larger than one, several CDW phases appear.

cond-mat.quant-gas↗