光計測を用いて，様々な物質の自発的な揺らぎを測定し，理論解析しました．ルビジウム原子の他の分子気体中のランダムウォークを初めて直接観測し，そして金属の反射率の自発的揺らぎを初めて観測しました．内部の揺らぎも測定することにより，光断層撮影で，各層の物質の揺らぎスペクトルを測定する方法を開発しました．氷表面の薄い液状層の厚みを測定しました．さらに層が水の性質を持つことを示し，厚みの2次元的な変化も初めて測定しました．これらの光計測ではいずれも我々の開発した散射雑音の除去法を用いており，重要な役割を果たしています．
また，格子系を用いて，温度の基本的な性質と非線形振動の定常モードを分析しました．
Properties of spontaneous fluctuations were investigated in various materials, through optical measurements, and analyzed from theory. Random walks of Rubidium atoms were observed directly. Atomic random walks had not been previously observed. Reflectance fluctuations in metals were observed for the first time, and their properties were investigated. A method to measure the fluctuation spectra of internal layers in optical coherence tomography was developed, and demonstrated. Surface melting of ice was investigated, and the thickness of the liquid-like layer was measured, through surface fluctuations. Furthermore, the properties of the liquid-like layer were analyzed, and were found to be similar to those of liquid water. In all these optical measurements, the reduction of shot-noise was essential to obtaining the results. Using lattice systems, basic properties, and the definition of temperature were studied. Furthermore, non-linear normal modes were studied systematically.

研究種目 : 基盤研究 (C) (一般)
研究期間 : 2015～2019
課題番号 : 15K05217
研究分野 : 非平衡物理学