  Decoherence time has been calculated for an optical ion trap of Be atoms in a
bistable potential model. Comparison has been made between decoherence time and
Zeno time for double well potential as a special case. Zeno time is considered
as a lower limit of decoherence time for sustainable quantum coherence.
Equality of the respective timescales provides a certain transitional
temperature, below which decoherence can be asymptotically minimized.
