Intense laser interacts with a beam of relativistic electrons. The laser is strong enough to make the electrons emit very energetic photons, that decay into electron-positron pairs. But, more than that, the electrons lose lots of their energy in this interaction – enough that the light pressure of the laser can reflect them like a mirror. Some of the electrons and positrons end up “following” the laser, and if the interaction is long enough, they may even be accelerated together.

Generating abundance of antimatter in laboratory is of great importance both for fundamental science and potential applications. Several scenarios have been envisaged to create plasma clouds (or beams) with approximately equal number of electrons and positrons, dense enough to exhibit collective behaviour. The aim is to study their self-consistent dynamics in conditions that match the ones the pair plasmas experience in space. Electron-positron pairs populate the magnetospheres of pulsars, and are believed to participate in the formation of gamma-ray bursts. It is therefore vital to study the collective processes under extreme intensities, which may play a key role in the global dynamics of pulsar magnetospheres. The new generation of laser facilities is expected to deliver short (10 fs–100 fs) laser pulses with 10–100 PW of peak power. This opens an opportunity to study matter at extreme intensities in the laboratory and provides access to new physics. Apart from laboratory astrophysics, electron-positron pairs have a number of other prospective applications that span from tests of fundamental symmetries in the laws of physics and studies of antimatter gravity to the characterisation of materials. Here we propose a configuration that allows to both create and accelerate an electron-positron beam.The new particles are generated in the laser focus and gain relativistic momentum in the direction of laser propagation. Short focal length is an advantage, as it allows the particles to be ejected from the focal region with a net energy gain in vacuum.Due to the laser defocusing, the trapped particles remain in the laser field only a fraction of a full oscillation cycle. This limits the maximum energy they can attain, but allows for a net energy transfer in vacuum that would otherwise be impossible. This setup produces a quasi-neutral electron-positron flow that can reach multi-GeV energies. A distinguishing aspect of this scheme is to produce at extreme intensities an equal number of electrons and positrons that can be separated from the initial electron beam and can be collected separately.

Modelling plasma physics phenomena accurately is computationally expensive. A single full 3D simulation can necessitate over 10M CPUh (or ~100k USD). Furthermore, adding Monte Carlo sampling to simulate strong field quantum electrodynamical processes (SFQED) exacerbates the problem, making these simulations impractical and expensive. Recently, quantum computing has emerged as a potential alternative to classical computing, offering significant speedups over classical calculations. Additionally, it can also provide a native simulation of quantum phenomena, which classical computers struggle to replicate. Thus, we are preparing frameworks which allow plasma physics and SFQED to be simulated with quantum computers to leverage the unique advantages these novel technologies can offer.