We calculate the entropy-temperature curves for non-interacting bosons in a 3D optical lattice and a 2D lattice with transverse harmonic confinement for ranges of depths and filling factors relevant to current experiments. These curves predict regimes where adiabatically changing the lattice depth will cause heating or cooling of the atomic sample. We indicate the critical points for condensation in the presence of a lattice and demonstrate regimes where reversible condensation should be possible by changing the lattice depth. We discuss the effects of interactions on our results and consider non-adiabatic processes.
Physical Review A (Atomic, Molecular and Optical Physics)