Nonadiabatic decay of metastable states on coupled linear potentials

Metastable quantum states can form in potential wells emerging from diabatic potentials with opposite slopes and a constant coupling. We investigate nonadiabatic decay of these metastable states on avoided crossings (MSACs) using diabatic and adiabatic representations arising from using Born-Huang theory.  Problems of this type arise in various systems in atomic and molecular physics. Examples include atom trapping with RF dressed potentials, formation of Rydberg molecules, etc. We compute the lifetimes of MSACs using 6 different non-perturbative quantum methods, all of which give results that agree well with each other. Time-dependent perturbation theory yields approximate lifetimes that deviate by 30% or less from the non-perturbative results. Lifetime predictions using a semi-classical Landau-Zener model are found to be off by up to a factor of twenty.