  We present a detailed study to show the possibility of approaching the
quantum ground-state of a hybrid optomechanical quantum device formed by a
Bose-Einstein condensate (BEC) confined inside a high-finesse optical cavity
with an oscillatory end mirror. Cooling is achieved using two experimentally
realizable schemes: back-action cooling and cold damping quantum feedback
cooling. In both the schemes, we found that increasing the two body atom-atom
interaction brings the mechanical oscillator to its quantum ground state. It
has been observed that back-action cooling is more effective in the good cavity
limit while the cold damping cooling scheme is more relevant in the bad cavity
limit. It is also shown that in the cold damping scheme, the device is more
efficient in the presence of BEC than in the absence of BEC.
