  We explore the asymmetric sequential Landau-Zener (LZ) dynamics in an
ensemble of interacting Bose condensed two-level atoms coupled with a cavity
field. Assuming the couplings between all atoms and the cavity field are
identical, the interplay between atom-atom interaction and detuning may lead to
a series of LZ transitions. Unlike the conventional sequential LZ transitions,
which are symmetric to the zero detuning, the LZ transitions of Bose condensed
atoms in a cavity field are asymmetric and sensitively depend on the photon
number distribution of the cavity. In LZ processes involving single excitation
numbers, both the variance of the relative atom number and the step slope of
the sequential population ladder are asymmetric, and the asymmetry become more
significant for smaller excitation numbers. Furthermore, in LZ processes
involving multiple excitation numbers, there may appear asymmetric population
ladders with decreasing step heights. During a dynamical LZ process, due to the
atom-cavity coupling, the cavity field shows dynamical collapse and revivals.
In comparison with the symmetric LZ transitions in a classical field, the
asymmetric LZ transitions in a cavity field originate from the
photon-number-dependent Rabi frequency. The asymmetric sequential LZ dynamics
of Bose condensed atoms in a cavity field may open up a new way to explore the
fundamental many-body physics in coupled atom-photon systems.
