In 1930, Stern and Estermann observed the diffraction of He atom scattered off the crystal surface of lithium flouoride [ref]. Despite this experimental demonstration of atomic matter-wave, further studies were halted until the 1980s. This is mainly because of its difficulty to control the motion of the atoms while preserving their coherence, which is prerequisite for matter-wave optics. Unlike neutrons and electrons whose motions can be easily affected by the optical force exerted by electromagnetic waves and collision against solid surface, the optical force upon neutral atom is very weak and colliding atoms normally stick to the surface of the material rather than being reflected or diffracted due to the atom-surface interaction, which causes decoherence on atomic waves. In other words, neither electromagnetic waves nor physical materials are suitable ways to manipulate atoms.
Meanwhile, various methods to manipulate particles have been studied both theoretically and experimentally over the past few decades(1-3). Those earlier studies have led to the success of laser atomic-cooling and -trapping which have given rise to the creation of ultracold atoms[MOT, Sisyphus, molasses, zeeman]. Ultracold atoms turned out to be a powerful tool to realize the atomic optics by allowing us to prepare sources of coherent atomic waves [quantum ref Shimizu, MIT, interf]. quantum reflection 넣을까.. ? Thus, the development of atom optics has been opened up based on those studies of controlling the motion of the atoms.
Furthremore, advanced technical developments in laser and nanotechnology have provided a major breakthrough in developing proper optical instruments such as mirrors and gratings. At an earlier stage, laser-tuning enables us to observe Bragg scattering and Kapitza-Dirac effect of atomic waves by adjusting detuning frequency[ref] and it motivated the first approach(or implementation of) to the practical atomic mirror which refers to as evanescent wave mirror [ref]. Besides, establishment of nano-fabricated devices can serve as matter-wave optics such as transmission grating[ref] and Fresnel zone plate[ref].
However, (further application/studies are in need of understanding of atom-surface interaction, size-limit, ultracold atom base 면 cluster study 불가능, )
QR 은 atom-surface interaction 을 이해하는 좋은 툴이자 좋은 mirror 이다. 근데 이거가 ultracold 일수도 있고 ㅇㅇㅇㅇㅇㅇㅇㅇㅇㅇ
Recently - half plane을 받을지... qr을 받을지.. , a totally new mechanism of matter-wave reflection has been demonstrated by observing quantum refleciton of metastable neon atoms from the solid surface. Quantum reflection is