Background-Free Quantum X-ray Optics

X-ray quantum optics is a rapidly advancing field dedicated to enhancing measurement precision through the utilization of quantum properties inherent in x-ray photons. A key technique for generating quantum states with x-ray radiation involves parametric down-conversion. However, a significant challenge arises from the concurrent generation of significantly stronger Compton-scattered radiation that directly impacts the object, hindering the realization of typical benefits such as dose reduction and enhanced sensitivity associated with quantum radiation. In response to this challenge, we propose employing a mosaic crystal to effectively manage the broad spectrum of quantum states and filter out undesired Compton radiation. We anticipate that the approach we will demonstrate will become the standard procedure for observing x-ray photon pairs. The success of this demonstration holds the potential to revolutionize the application of x-ray quantum states.