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Recently, experiments using high-Q massive mechanical oscillators have been proposed for testing quantum mechanics  and probing Planck scale physics . The basic requirements for these experiments is reduction of the thermal decoherence rate, i.e. the inverse time of the absorption of a phonon from the environment, under the mechanical resonance. When suspended massive mirror is used, thermal decoherence can be reduced by optically trapping the mirror's motion because high-frequency laser is almost in its ground state with low entropy, and can create an effectively zero-temperature thermal bath even at room temperature. This optical control of a macroscopic oscillator is stably achieved by using a triangular optical cavity .
I try to cool the mg-scale suspended mirror down to its motional ground state, and keep the state over one mechanical period by reducing the thermal decoherence rate.
 W. Marshall, C. Simon, R. Penrose, and D. Bouwmeester, "Towards Quantum Superpositions of a Mirror", Phys. Rev. Lett. 91, 130401 (2003).
 I. Pikovski, M. R. Vanner, M. Aspelmeyer, M. S. Kim, and C. Brukner, "Probing Planck-scale physics with quantum optics", Nat. Phys. 8, 393 (2012).
 N. Matsumoto, Y. Michimura, Y. Aso, and K. Tsubono, "Optically trapped mirror for reaching the standard quantum limit", Opt. Express 22, 12915 (2014).