the development of accurate atomic clocks, atom lithography and degerate gasses such as Bose-Einstein condensates (BECs). The ultracold atom 
driven by desire to
without surface -> surface
in various fields such as  
universal // general condition,, generality for different particles.
in honor of their pioneering suggestion
For this to happen
 

1.1 van der Waals interaction (nano-technology../ importance etc..)

 The dispersive interaction induced by electromagnetic vacuum fluctuations is an attractive long-range interaction between polarizable objects. The dispersion interaction between a particle and surface can be classified into two types depending on the distance z from the surface. The van der Waals (vdW) potential is dominant where the particles are closer to the surface while the Casimir-Polder (CP) potential is dominant for particles which are farther away from the surface. Because quantum reflection occurs at this omnipresent dispersive potential, we can practically investigate both retarded and non-retarded van der Waals coefficients for any kind of atom/molecule-surface interactions.

1.2 Quantum Reflection

 Quantum reflection is a quantum mechanical phenomenon in which a particle is reflected by the attractive part of the van der Waals potential as depicted in Fig. 1(a). Unlike classical reflection, a particle does not need to collide with the surface because quantum reflection typically occurs tens of nanometers away from the surface. In order to investigate quantum reflection experimentally, the particle’s kinetic energy perpendicular to the surface must be sufficiently small. One way to achieve this prerequisite is using a grazing incidence condition. Fig. 1(b) shows a sketch of the grazing incidence condition. In typical experimental conditions, a grazing incidence angle qin of a few mrads provides a sufficiently small z-component kinetic energy Ez. perpendicular to the surface

1.3 Matter-wave diffraction from a periodic array of half planes

Theory

1.1 QR - semiclassical approach - sam's code(brief explanation about two competing theoretical model)

--- least squares analysis (logarithmic)

1.2 Half plane  - original/ Attenuation

- the possibility to observe the diffraction of N2 of He3 - theoretical curve with the square-wave grating