  Radiation damage is one of the most severe resolution limiting factors in
x-ray imaging, especially relevant to biological samples. One way of
circumventing this problem is to exploit correlation-based methods developed in
quantum imaging. Among these, there is ghost imaging (GI) in which the image is
formed by radiation that has never interacted with the sample. Here, we
demonstrate GI at an XUV free-electron laser by utilizing correlation
techniques. We discuss the experimental challenges, optimal setup, and crucial
ingredients to maximize the achievable resolution.
