The existence of an isolated band in a system of three particles in an optical lattice

TL;DR

This paper proves the existence of isolated energy bands in two- and three-boson systems on a lattice, demonstrating bound states for particles interacting via zero-range potentials, which has implications for optical lattice physics.

Contribution

It establishes the existence of bound states and an isolated energy band in multi-particle lattice systems with zero-range interactions, extending understanding of bosonic systems in optical lattices.

Findings

Existence of two- and three-particle bound states.

Presence of an isolated energy band in the spectrum.

Results hold for both attractive and repulsive interactions.

Abstract

We prove the existence of two-and three-particle bound states of the Schr\"odinger operators $h_\mu(k),k\in \T^d$ and $H_\mu(K),K\in \T^d$ associated to Hamiltonians $\mathrm{h}_{\mu}$ and $\mathrm{H}_{\mu}$ of a system of two and three identical bosons on the lattice $\Z^d, d=1,2$ interacting via pairwise zero-range attractive $\mu<0$ or repulsive $\mu>0$ potentials. As a consequence we show the existence of an isolated band in the two and three bosonic systems in an optical lattice.