Researchers from the University of Oxford and Instituto Superior Tecnico in Lisbon have run real-time 3D simulations showing how intense laser beams interact with the quantum vacuum—a space that’s not truly empty but filled with short-lived electron-positron pairs. Their work, published in Communications Physics, offers a close look at what happens when light appears to come from "darkness", something which is a bit like magic in terms of classical physics.
Using a highly advanced version of the OSIRIS (short for Outdoor Scene and InfraRed Image Simulation) sim software, the team recreated a phenomenon called vacuum four-wave mixing. In this process, the electromagnetic fields from three strong laser pulses polarize the virtual particles in the vacuum, causing photons to bounce off one another—resulting in a fourth laser beam.
“This is not just an academic curiosity – it is a major step toward experimental confirmation of quantum effects that until now have been mostly theoretical,” said Professor Peter Norreys from Oxford’s Department of Physics.
What makes this work timely is the global rollout of multi-Petawatt laser systems that can generate extremely strong electromagnetic fields. Facilities like Vulcan 20-20 in the UK, ELI in Europe, and SHINE and SEL in China, along with the OPAL (optical parametric amplifier line) dual-beam laser in the U.S., are expected to hit the power levels needed to see these rare quantum effects in actual experiments.
To make their simulations more accurate, the researchers used a semi-classical numerical solver based on the Heisenberg-Euler Lagrangian. This approach allowed them to model two major quantum vacuum effects and check their results against known predictions for vacuum birefringence—a phenomenon where light splits or shifts as it passes through a strong electromagnetic field.
They tested both plane-wave and Gaussian laser pulses, and found their outputs matched well with existing theories. For the four-wave mixing case, they used three Gaussian beams and were able to track the formation of the fourth beam over time. The simulation also showed a bit of astigmatism—where the output beam wasn’t perfectly shaped—and gave clear measurements of how long the interaction lasted and how big the affected area was.
“Our computer program gives us a time-resolved, 3D window into quantum vacuum interactions that were previously out of reach,” said lead author Zixin Zhang, a doctoral student at Oxford. “By applying our model to a three-beam scattering experiment, we were able to capture the full range of quantum signatures, along with detailed insights into the interaction region and key time scales.”
The team compared their results with simpler models and past data to make sure everything checked out. These tools are expected to help scientists design real-life experiments, with more control over laser timing, shape, and direction.
Professor Luis Silva, co-author from Instituto Superior Técnico and Visiting Professor at Oxford, said: “A wide range of planned experiments at the most advanced laser facilities will be greatly assisted by our new computational method implemented in OSIRIS. The combination of ultra-intense lasers, state-of-the-art detection, cutting-edge analytical and numerical modelling are the foundations for a new era in laser-matter interactions, which will open new horizons for fundamental physics.”
The simulation tool may also help in the search for new particles, such as axions and millicharged particles, which are considered strong candidates for dark matter.
Source: Oxford University, Nature
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