  Generation of single-photon entanglement is discussed in nuclear forward
scattering. Using successive switchings of the direction of the nuclear
hyperfine magnetic field, the coherent scattering of photons on nuclei is
controlled such that two signal pulses are generated out of one initial pump
pulse. The two time-resolved correlated signal pulses have different
polarizations and energy in the keV regime. Spatial separation of the entangled
field modes and extraction of the signal from the background can be achieved
with the help of state-of-the-art x-ray polarizers and piezoelectric fast
steering mirrors.
