Authors: George Rajna
Thanks to a new technique developed at EPFL, optical diffraction gratings can now be made out of pure diamond, with their surfaces smoothed down to the very last atom.  When Israeli scientist Daniel Shechtman first saw a quasicrystal through his microscope in 1982, he reportedly thought to himself, "Eyn chaya kazo"— Hebrew for, "There can be no such creature."  Washington State University physicists have found a way to write an electrical circuit into a crystal, opening up the possibility of transparent, three-dimensional electronics that, like an Etch A Sketch, can be erased and reconfigured.  A new technique developed by MIT researchers reveals the inner details of photonic crystals, synthetic materials whose exotic optical properties are the subject of widespread research.  In experiments at SLAC, intense laser light (red) shining through a magnesium oxide crystal excited the outermost " valence " electrons of oxygen atoms deep inside it.  LCLS works like an extraordinary strobe light: Its ultrabright X-rays take snapshots of materials with atomic resolution and capture motions as fast as a few femtoseconds, or millionths of a billionth of a second. For comparison, one femtosecond is to a second what seven minutes is to the age of the universe.  A 'nonlinear' effect that seemingly turns materials transparent is seen for the first time in X-rays at SLAC's LCLS.  Leiden physicists have manipulated light with large artificial atoms, so-called quantum dots. Before, this has only been accomplished with actual atoms. It is an important step toward light-based quantum technology.  In a tiny quantum prison, electrons behave quite differently as compared to their counterparts in free space. They can only occupy discrete energy levels, much like the electrons in an atom-for this reason, such electron prisons are often called "artificial atoms".  When two atoms are placed in a small chamber enclosed by mirrors, they can simultaneously absorb a single photon.  Optical quantum technologies are based on the interactions of atoms and photons at the single-particle level, and so require sources of single photons.
Comments: 40 Pages.
[v1] 2017-09-05 07:36:43
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