Anomalous Fluctuation In Macroscopic Physics System:Realization Of Key Techniques Towards Macroscopic Quantum Effects

Fluctuation prevails in any physical system at finite temperature. By ob-serving fluctuation, we not only can understand dissipation of classical system, but also can shed light on the decoherence process of quantum system. Com-monly, macroscopic system fluctuates and behaviors classically while system at micro-scale, such a single atom or spin, follows quantum mechanics. Such tran-sition from quantum reciprocity to classical non-reciprocity, when system goes from micro to macro, is always confusing physicists ever since the birth of quan-tum mechanics, and more interesting, how macroscopic are quantum mechanics could emerge are still unclear. The deep understanding and control of fluctuation of complicated and macro-scale system therefore play important role for exploring these problem.The recently developed new techniques such as superconducting, superfluid, cold atoms, spin ensemble, and nano-mechanics provided platforms for us to s-tudy these problem. These system on one hand are much macro in either size of complexity than traditional single quantum system, on the other hand, do they emerges quantum effects at specific condition, especially, nano-mechanics is now at the central position in quantum science research.In this thesis, we set up home built experimental systems and explored fluc-tuation dynamics of a quasi-macroscopic system and macroscopic one. By using new developed experimental techniques, we discovered new and anomalous fluc-tuation dynamics that never be observed before, these results pave the way to study macroscopic quantum process in the future.1. Based on single electron spin quantum interferometer as a probe, we study the fluctuation dynamics of a nuclear ensemble, a quasi-macroscopic system consist large number of particles. We first realized Landau-Zener interfer-ometry process using the electron spin, which make us precisely measured the strength of the fluctuation. Especially, under the dynamical decoupling control, a quantum behavior of the ensemble are observed for the first time.2. To further explore fluctuation dynamics of real macroscopic system, we de-sign and set up a system that study the nano-mechanical system, by con-structing a home-build optical interferometer, we observed thermal fluctua- tion of a nano-mechanical resonator at the rom temperature, specially, we demonstrate a parametrical conversion process which suppressed the mea-surement noise effectively, it provided potential method for realize quantum limited detection of mechanical resonator in the future.3. However, Fluctuations at room temperature is too strong and masks any possible macroscopic quantum effects. We further set up a low temperature system to study macroscopic mechanical system dynamics. By exploring the mechanical character in deforming a single chemical bond, we realized the strongest nonlinear response in mechanical system. Such strong non-linear response made us observed thermal fluctuation dynamics of bi-states transition in a nano-mechanical resonator, a phenomena that is theoretical-ly studied but never observed in macroscopic solid system. The results is an important step towards quantum fluctuation induced bi-states tunnel-ing and other macroscopic quantum process using mechanical system in the future.