Strong-field QED in laser-electron beam collisions

David A. Reis

Stanford PULSE Institute

Strong-field light matter interactions areubiquitous in the optical regime, wheretunnel ionization leads to such phenom-ena as high-harmonic generation and above-threshold ionization. For x rays, nonlinearinteractions have only recently become ac-cessible using free-electron lasers such as theLCLS[1, 2]. At sufficiently high fields, eventhe vacuum becomes nonlinear. Here tunnelionization of the vacuum can produce copi-ous electron-positron pairs at field strengthscomparable to the electron mass in a Comp-ton wavelength[3]. Such fields are orders ofmagnitude away from what is possible witheven the most intense lasers, but are expectedto occur in various astrophysical phenomenaas well as in beam-beam collisions in futurelepton colliders. Importantly, they can alsooccur in the collisions of high energy electronsor photons with a strong laser field.

Figure 1: Intensity dependence of multiphotonBreit-Wheeler from E144 experiment.

In this talk, I will discuss efforts to sys-tematically explore the strong-field regime ofQED, including at the FACET-II facility atSLAC. I will describe what we expect to seeand how this differs qualitatively from pertur-bative QED, such as was studied two decadesago on the seminal SLAC Experiment-144,including multi-photon Breit-Wheeler pairproduction [4, 5], Fig. 1.

[1] S. Shwartz, et al., X-ray second harmonicgeneration. Phys. Rev. Lett., 112:163901,2014.

[2] M. Fuchs, et al., Anomalous nonlinearx-ray Compton scattering. Nat Phys,11:964–970, 11 2015.

[3] Di Piazza et al., Rev. Mod. Phys. Ex-tremely high-intensity laser interactionswith fundamental quantum systems. 84,1177, 2012.

[4] D. L. Burke, et al., Positron productionin multiphoton light-by-light scattering.Phys. Rev. Lett., 79:1626–1629, 1997.

[5] C. Bamber, et al. Studies of nonlinear QEDin collisions of 46.6 GeV electrons with in-tense laser pulses. Phys. Rev. D, 60:092004,1999.

This abstract was submitted to PQE-2019, the 49th Winter Colloquium on the Physics of Quantum Electronics.Submitted by David A. Reis on Sat Dec 8 19:53:27 CST 2018.See the program for placement of this presentation.