Phase Diagram of Bosons in Two-Color Superlattices from Experimental Parameters

TL;DR

This paper maps experimental parameters of a bosonic gas in a two-color superlattice to a Bose-Hubbard model and uses DMRG to analyze the phase diagram, identifying superfluid, Mott-insulator, and Bose-glass phases.

Contribution

It provides a direct method to study quantum phases from experimental laser parameters using explicit band-structure calculations and DMRG.

Findings

Identifies phase boundaries between superfluid, Mott-insulator, and Bose-glass phases.

Shows all relevant quantum phases can be controlled via laser intensities.

Provides a practical approach to analyze experimental setups without additional tuning.

Abstract

We study the zero-temperature phase diagram of a gas of bosonic 87-Rb atoms in two-color superlattice potentials starting directly from the experimental parameters, such as wavelengths and intensities of the two lasers generating the superlattice. In a first step, we map the experimental setup to a Bose-Hubbard Hamiltonian with site-dependent parameters through explicit band-structure calculations. In the second step, we solve the many-body problem using the density-matrix renormalization group (DMRG) approach and compute observables such as energy gap, condensate fraction, maximum number fluctuations and visibility of interference fringes. We study the phase diagram as function of the laser intensities s_2 and s_1 as control parameters and show that all relevant quantum phases, i.e. superfluid, Mott-insulator, and quasi Bose-glass phase, and the transitions between them can be investigated through a variation of these intensities alone.