Casimir Energy, Holographic Dark Energy and Electromagnetic Metamaterial
  Mimicking de Sitter
  We compute the Casimir energy of the photon field in a de Sitter space and
find it to be proportional to the size of the horizon, the same form of the
holographic dark energy. We suggest to make metamaterials to mimic de Sitter
space in laboratory and measure the predicted Casimir energy.
