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Institutsseminar
Description

Detection Schemes for Vacuum Birefringence With a Case Study for PW-class Lasers and Optical Probes

Dr. Stefan Ataman
ELI-NP, Bucharest

Abstract:

The still to be tested predictions of quantum electrodynamics are the ones stemming from the non-perturbative regime described by the Heisenberg-Euler (HE) Lagrangian [1]. They include  phenomena such as light-by-light scattering [2], light splitting [3] and vacuum birefringence (VBir) [4]. The latter is addressed in this talk. The theoretical as well as experimental efforts in order to measure VBir are briefly detailed, including the magnetic field-based experiments as well as the x-ray and γ-ray probes with petawatt (PW) laser pump proposals. We elaborate on the feasibility of an interferometric, all-optical, Mach-Zehnder-based VBir experiment [5]. The experimental proposal is based on a pump-probe configuration combining a 10 PW pump laser and a lower power pulsed probe beam. Taking into account realistic pump laser parameters (30 fs pulse duration and a focus waist 3-5 µm), for a nearly counter-propagating probe laser beam the ideal probe duration is found to be significantly longer (100 to 700 fs), thus allowing a lower minimum required probe power. We discuss in detail an experimental scheme able to implement the required pump-probe interaction geometry. In order to mitigate the undesired effect of mechanical vibrations,  we also put forward an automatic compensation mechanism, able to significantly reduce this unwanted effect. Finally, we discuss avenues of further improvement via the employment of non-classical states of light for the probe beam, namely the coherent plus squeezed vacuum input. Given today's technology, keeping the same probe power and employing the squeezed vacuum input leads to an improvement of one order of magnitude in the expected interferometric phase sensitivity.

[1] W. Heisenberg and H. Euler, “Folgerungen aus der Diracschen Theorie des Positrons”, Z. Physik 98, 714 (1936).

[2] R. Karplus, M. Neuman, “Scattering Processes Produced by Electrons in Negative Energy States”, Phys. Rev., 83, 776 (1951).

[3] Z. Bialynicka-Birula and I. Bialynicki-Birula, “Nonlinear Effects in Quantum Electrodynamics. Photon Propagation and Photon Splitting in an External Field”, Phys. Rev. D, 2, 2341 (1970); F. Karbstein, “Probing Vacuum Polarization Effects with High-Intensity Lasers”, Particles 3, 39 (2020)

[4] J. J. Klein and B. P. Nigam, “Birefringence of the vacuum”, Phys. Rev., 135, B1279 (1964).

[5] S. Ataman, “Vacuum birefringence detection in all-optical scenarios”, Phys. Rev. A, 97, 063811 (2018);  “Vacuum Birefringence Measurement via All-Optical Interferometric Schemes”, J. Phys.: Conf. Ser. 2494 012019 (2023); S. Ataman  et al., “All-Optical Vacuum Birefringence with PW-Class Lasers: Case Study for the ELI-NP Parameters”, J. Phys.: Conf. Ser. 2894 012020 (2023).

Location
Seminarraum HI-Jena, Fröbelstieg 3
Date
06.02.2025