  A new quantum eraser setup exploiting for the first time the time-energy
complementarity relation in the x-ray regime is investigated theoretically.
Starting point is the interference process between x-ray quanta driving two
nuclear hyperfine transitions in a nuclear forward scattering setup. We show
that which-way information can be obtained by marking the scattering paths with
orthogonal polarization states, thus leading to the disappearance of the
interference pattern. In turn, erasure of the which-way information leads to
the reappearance of the interference fringes. We put forward two schemes using
resonant scattering off nuclear targets and design which-way marking procedures
to realize the quantum eraser setup for x-ray quanta.
