QED-driven laser absorption

Absorption covers the physical processes which convert intense photon flux into energetic particles when a high-power laser (I \textgreater 10$^{\mathrm{18}}$ W cm$^{\mathrm{-2}}$ where I is intensity at 1$\mu $m wavelength) illuminates optically-thick matter.~It underpins important applications of petawatt laser systems today, e.g., in isochoric heating of materials. Next-generation lasers such as ELI are anticipated to produce quantum electrodynamical (QED) bursts of $\gamma $-rays and anti-matter via the multiphoton Breit-Wheeler process which could enable scaled laboratory probes, e.g., of black hole winds. Here, applying strong-field QED to advances in plasma kinematic theory, we present a model elucidating absorption limited only by an avalanche of self-created electron-positron pairs at ultra-high-field. The model, confirmed by multidimensional QED-PIC simulations, works over six orders of magnitude in optical intensity and reveals this cascade is initiated at 1.8 x 10$^{\mathrm{25}}$ W cm$^{\mathrm{-2}}$ using a realistic linearly-polarized laser pulse. Here the laser couples its energy into highly-collimated electrons, ions, $\gamma $-rays, and positrons at 12{\%}, 6{\%}, 58{\%} and 13{\%} efficiency, respectively. We remark on attributes of the QED plasma state and possible applications.