On the Observation of Vacuum Birefringence

Abstract

We suggest an experiment to observe vacuum birefringence induced by intense laser fields. A high-intensity laser pulse is focused to ultra-relativistic intensity and polarizes the vacuum which then acts like a birefringent medium. The latter is probed by a linearly polarized x-ray pulse. We calculate the resulting ellipticity signal within strong-field QED assuming Gaussian beams. The laser technology required for detecting the signal will be available within the next three years.

Figures (1)

• Figure 1: Proposed experimental setup for the demonstration of vacuum birefringence: A high-intensity laser pulse is focused by an $F/2.5$ off-axis parabolic mirror. A hole is drilled into the parabolic mirror in alignment with the $z$-axis (axes as indicated) in such a way that an x-ray pulse can propagate along the $z$-axis through the focal region of the high-intensity laser pulse. Using a polarizer-analyzer pair the ellipticity of the x-ray pulse may be detected. Shown in grey: Extension of the setup for the generation of counter propagating laser pulses and a high-intensity standing wave which may be used for pair creation.