Detectable Optical Signatures of QED Vacuum Nonlinearities Using High-Intensity Laser Fields

Abstract

Up to date, quantum electrodynamics (QED) is the most precisely tested quantum field theory. Nevertheless, particularly in the high-intensity regime it predicts various phenomena that so far have not directly been accessible in all-optical experiments, such as photon-photon scattering phenomena induced by quantum vacuum fluctuations. Here, we focus on all-optical signatures of quantum vacuum effects accessible in the high-intensity regime of electromagnetic fields. We present an experimental setup giving rise to signal photons distinguishable from the background. This configuration is based on two optical pulsed petawatt lasers: one generates a narrow but high-intensity scattering center to be probed by the other one. We calculate the differential number of signal photons attainable with this field configuration analytically and compare it with the background of the driving laser beams. arXiv:2001.05731v2 [physics.optics]

Numerical Simulations of the Nonlinear Quantum Vacuum in the Heisenberg-Euler Weak-Field Expansion

“…Furthermore, it is the authors' aim to provide colleagues in the research group who study optical signatures of vacuum effects in high intensity fields with numerical results. To this end it will be attempted to reproduce the settings and findings of [31,[33][34][35]. The goal is to provide an indispensable tool for experimentalists to second their setups with simulation data.…”

“…However, the derivative in (35) can also be approximated for a forward propagating mode g + by a first order forward finite difference. In this case (36) can be written as…”

“…Next, the derivative in (35) for the backward propagating part can be approximated by a first order backward finite difference. In this case (36) can be approximated for the backward propagating case as…”

“…Almost all analytical approaches found in the literature to compute nonlinear vacuum effects, e.g. as in [7,12,14,17,[22][23][24][25][26][27][28][29][30][31][32][33][34][35] have shortcomings. As a consequence these attempts are still limited to simple scenarios which most of the time are inappropriate for experimental verification.…”

Experimental estimates of the photon background in a potential light-by-light scattering study

“…In order to maximize chances of detecting scattered photons, one ideally chooses a parameter space (angular, polarization and spectral) that is not occupied by photons from the driving pulses. The optimization of the ratio of scattered photons over primary photons, often referred to as discernible photons, has been addressed in a number of theoretical studies [15,17,[21][22][23]. While a separation of emission directions and spectra can be achieved for example by frequency doubling one of the beams, employing more than two beams or measuring sum frequencies such as the third harmonic, the interaction of two colliding laser pulses with fundamental frequency remains the simplest experimental configuration and promises highest absolute yields.…”