X-ray polarimetry and its application to strong-field quantum electrodynamics

Polarimetry is a highly sensitive method to quantify changes of the polarization state of light when passing through matter and is therefore widely applied in material science. The progress of synchrotron and X-ray free electron laser (XFEL) sources has led to significant developments of X-ray polarizers, opening perspectives for new applications of polarimetry to study source and beamline parameters as well as sample characteristics. X-ray polarimetry has shown to date a polarization purity of less than $1.4\times {10}<^>{-11}$, enabling the detection of very small signals from ultrafast phenomena. A prominent application is the detection of vacuum birefringence. Vacuum birefringence is predicted in quantum electrodynamics and is expected to be probed by combining an XFEL with a petawatt-class optical laser. We review how source and optical elements affect X-ray polarimeters in general and which qualities are required for the detection of vacuum birefringence.

Automated summary

Polarimetry is a highly sensitive method used in material science to quantify changes of the polarization state of light when passing through matter. The development of synchrotron and XFEL sources has greatly improved X-ray polarizers, allowing for new applications in studying source and beamline parameters as well as sample characteristics. One important application is the detection of vacuum birefringence, which can be probed by combining an XFEL with a petawatt-class optical laser. This article reviews the impact of source and optical elements on X-ray polarimeters and the required qualities for detecting vacuum birefringence.