arXiv:1311.1284 · Physical Review A
Existence of an energy gap in a one-dimensional Lesanovsky model
Hosho Katsura
Abstract
We study the quantum lattice gas model in one dimension introduced by Lesanovsky [Lesanovsky, Phys. Rev. Lett. 108, 105301 (2012)], who showed that the exact ground state and a couple of excited states can be obtained analytically. The Hamiltonian of the model depends solely on the parameter $z$, the meaning of which is a fugacity in the corresponding classical lattice gas model. For small $z$ ($0<z<1$), we prove that there is an energy gap between the ground state and the excited states by applying Knabe's method [Knabe, J. Stat. Phys. 52, 627 (1988)].