Electromagnetically Induced Transparency for X Rays

Electromagnetically induced transparency is predicted for x rays in laser-dressed neon gas. The x-ray photoabsorption cross section and polarizability near the Ne K edge are calculated using an ab initio theory suitable for optical strong-field problems. The laser wavelength is tuned close to the transition between 1s^-13s and 1s^-13p (∼800  nm). The minimum laser intensity required to observe electromagnetically induced transparency is of the order of 10¹²  W/cm². The ab initio results are discussed in terms of an exactly solvable three-level model. This work opens new opportunities for research with ultrafast x-ray sources.