  Einstein's general theory of relativity not only revolutionized human
understanding of the universe, but also brought many gravitational applications
in large scale, such as gravitational-wave astronomy, gravitational lensing,
and the operation of the global positioning system. However, it still remains a
challenge to implement applications for gravitational effects at small spacial
extensions on Earth. Here, we investigate a structured waveguide system that
allows for the control of an x-ray profile at altitude separations of
millimeters and even shorter using the nuclear resonant scattering of x rays.
Our present results suggest a potential compact scheme for turning the Earth's
gravity into a practical application of x-ray optics.
