Computational modelling of the semi-classical quantum vacuum in 3D

Communications Physics Springer Nature 8:1 (2025) 224

Authors:

Zixin Zhang, Ramy Aboushelbaya, Iustin Ouatu, Elliott Denis, Abigail James, Robin Timmis, Marko von der Leyen, Rui Torres, Thomas Grismayer, Luis O Silva

Abstract:

The global commissioning of multi-Petawatt laser systems provides unprecedented access to ultra-high electromagnetic fields for probing the quantum vacuum. However, current analytical models are limited, necessitating large-scale simulations for experimental validation. Here, we present real-time three-dimensional simulations of two quantum vacuum effects, using a semi-classical numerical solver based on the Heisenberg-Euler Lagrangian. The simulation model is benchmarked against vacuum birefringence analytical results with a counter-propagating setup. Simulations results of both plane-wave and Gaussian pulses are consistent with theoretical predictions. The solver is then applied to four-wave mixing using three Gaussian pulses with real-time information on the harmonic evolution. We provide quantitative explanations for the astigmatism in the output and produce precise estimates of the interaction time and size. Results are compared with the plane-wave model and previous numerical results. This solver paves the way for in-depth investigations of a broad spectrum of quantum vacuum effects in any arbitrary laser setup.

High brightness, symmetric electron bunch generation in a plasma wakefield accelerator via a radially-polarized plasma photocathode

ArXiv 2505.11387 (2025)

Authors:

James Chappell, Emily Archer, Roman Walczak, Simon Hooker

Theory of x-ray photon correlation spectroscopy for multiscale flows

Physical Review Research American Physical Society (2025)

Authors:

Charles Heaton, Gianluca Gregori

Abstract:

Complex multiscale flows associated with instabilities and turbulence are commonly induced under High Energy Density (HED) conditions, but accurate measurement of their transport properties has been challenging. X-ray Photon Correlation Spectroscopy (XPCS) with coherent X-ray sources can, in principle, probe material dynamics to infer transport properties using time autocorrelation of density fluctuations. Here we develop a theoretical framework for utilizing XPCS to study material diffusivity in multiscale flows. We extend single-scale shear flow theories to broadband flows using a multiscale analysis that captures shear and diffusion dynamics. Our theory is validated with simulated XPCS for Brownian particles advected in multiscale flows. We demonstrate the versatility of the method over several orders of magnitude in timescale using sequential-pulse XPCS, single-pulse X-ray Speckle Visibility Spectroscopy (XSVS), and double-pulse XSVS.

Theory of x-ray photon correlation spectroscopy for multiscale flows

Physical Review Research American Physical Society (APS) 7:2 (2025) 023202

Authors:

Hao Yin, Charles Heaton, Eric G Blackman, Arianna E Gleason, Joshua J Turner, Gilbert W Collins, Gianluca Gregori, Jessica K Shang, Hussein Aluie

The structure of liquid carbon elucidated by in situ X-ray diffraction.

Nature (2025)

Authors:

D Kraus, J Rips, M Schörner, MG Stevenson, J Vorberger, D Ranjan, J Lütgert, B Heuser, JH Eggert, H-P Liermann, II Oleynik, S Pandolfi, R Redmer, A Sollier, C Strohm, TJ Volz, B Albertazzi, SJ Ali, L Antonelli, C Bähtz, OB Ball, S Banerjee, AB Belonoshko, CA Bolme, V Bouffetier, R Briggs, K Buakor, T Butcher, V Cerantola, J Chantel, AL Coleman, J Collier, GW Collins, AJ Comley, TE Cowan, G Cristoforetti, H Cynn, A Descamps, A Di Cicco, S Di Dio Cafiso, F Dorchies, MJ Duff, A Dwivedi, C Edwards, D Errandonea, S Galitskiy, E Galtier, H Ginestet, L Gizzi, A Gleason, S Göde, JM Gonzalez, MG Gorman, M Harmand, NJ Hartley, PG Heighway, C Hernandez-Gomez, A Higginbotham, H Höppner, RJ Husband, TM Hutchinson, H Hwang, DA Keen, J Kim, P Koester, Z Konôpková, A Krygier, L Labate, A Laso Garcia, AE Lazicki, Y Lee, P Mason, M Masruri, B Massani, EE McBride, JD McHardy, D McGonegle, C McGuire, RS McWilliams, S Merkel, G Morard, B Nagler, M Nakatsutsumi, K Nguyen-Cong, A-M Norton, N Ozaki, C Otzen, DJ Peake, A Pelka, KA Pereira, JP Phillips, C Prescher, TR Preston, L Randolph, A Ravasio, D Santamaria-Perez, DJ Savage, M Schölmerich, J-P Schwinkendorf, S Singh, J Smith, RF Smith, J Spear, C Spindloe, T-A Suer, M Tang, M Toncian, T Toncian, SJ Tracy, A Trapananti, CE Vennari, T Vinci, M Tyldesley, SC Vogel, JPS Walsh, JS Wark, JT Willman, L Wollenweber, U Zastrau, E Brambrink, K Appel, MI McMahon

Abstract:

Carbon has a central role in biology and organic chemistry, and its solid allotropes provide the basis of much of our modern technology1. However, the liquid form of carbon remains nearly uncharted2, and the structure of liquid carbon and most of its physical properties are essentially unknown3. But liquid carbon is relevant for modelling planetary interiors4,5 and the atmospheres of white dwarfs6, as an intermediate state for the synthesis of advanced carbon materials7,8, inertial confinement fusion implosions9, hypervelocity impact events on carbon materials10 and our general understanding of structured fluids at extreme conditions11. Here we present a precise structure measurement of liquid carbon at pressures of around 1 million atmospheres obtained by in situ X-ray diffraction at an X-ray free-electron laser. Our results show a complex fluid with transient bonding and approximately four nearest neighbours on average, in agreement with quantum molecular dynamics simulations. The obtained data substantiate the understanding of the liquid state of one of the most abundant elements in the universe and can test models of the melting line. The demonstrated experimental abilities open the path to performing similar studies of the structure of liquids composed of light elements at extreme conditions.