Atom Nanolithography with Atom Pinhole Camera
The most efficient method for controlling the motion of material particles in experimental physics is the use of interaction potentials with electromagnetic fields. The static magnetic and electric interaction potentials are used in the optics of charged particles. In the optics of neutral atoms, the various interaction potentials of atoms with laser and electromagnetic fields are used in addition to the static fields. The effective methods of diffraction, interference, mirror reflection of atoms are implemented in atom optics. The most difficult problem in atom optics is the problem of high-resolution focusing of neutral atoms, which is promising for the nondestructive method for probing the surface at the atomic level, as well as for the creation of nanostructures on the surface. Although there are many proposals for focusing of atomic beams, this problem is experimentally unsolved. The main difficulty is the creation of the interaction potential of the atom with the electromagnetic field that is close to an ideal lens for atoms.In this paper, we experimentally implement another approach to the problem of focusing and construction of an image in atom optics, which is based on a well known idea of optical pinhole camera. The pinhole camera in optics is a camera without lens. Light forming an image passes through a small hole. In our experiment with the atom pinhole camera the Cr atomic beam passes through a set of holes in a metal mask and thereby forms, by analogy with optics, a glowing object of a given geometry. The atoms pass through the holes in the mask, propagate in vacuum along rectilinear trajectories, similar to light rays, and are incident on a thin film (thickness 5 mum) placed at a distance of 90 mm from the mask with a large number (n =107-108 /cm2) of nanoholes (50 nm diameter). Each hole of the film is a pinhole camera for atoms, which forms its individual image of the object on the substrate surface placed at a distance of l = 5mum behind the film.
Atom “pinhole camera” with nanometer resolution
An atom “pinhole camera” with nanometer resolution has been experimentally implemented for the first time. Owing to the use of this camera, an array of ∼106 identical nanostructures of Cr atoms with a characteristic size of the nanostructure of less than 50 nm has been created on a glass surface. Nanostructures of arbitrary shapes have been created.
Imaging and focusing of an atomic beam with a large period standing light wave
A novel atomic lens scheme is reported. A cylindrical lens potential was created by a large period (⋍ 45 μm) standing light wave perpendicular to a beam of metastable He atoms. The lens aperture (25 μm) was centered in one antinode of the standing wave; the laser frequency was nearly resonant with the atomic transition 23S1−23P2 (λ=1.083 μm) and the interaction time was significantly shorter than the spontaneous lifetime (100 ns) of the excited state. The thickness of the lens was given by the laser beam waist (40 μm) in the direction of the atomic beam. Preliminary results are presented, where an atomic beam is focused down to a spot size of 4 μm. Also, a microfabricated grating with a period of 8 μm was imaged. We discuss the principle limitations of the spatial resolution of the lens given by spherical and chromatic aberrations as well as by diffraction. The fact that this lens is very thin offers new perspectives for deep focusing into the nm range.