MeVQE: A world-leading centre for MeV scale entanglement physics

This programme brings together an interdisciplinary consortium of researchers from the hadron physics, nuclear gamma ray spectroscopy, plasma physics and quantum information fields. It will enable UK leadership in a number of pioneering fundamental tests and applications of photon quantum entanglement in the largely unexplored Mega electronVolt (MeV) energy scale, often referred to as "gamma-photons". Measurement and exploitation of entanglement into this regime is facilitated by employing the latest quantum technologies in fast, cost effective and high-quality gamma-photon detection systems. At this MeV scale new and exciting possibilities in medical imaging and homeland security can be accessed which are currently out of reach from the more extensively studied optical regime.

The annihilation of the antiparticle of the electron (the positron) provides a source of quantum-entangled photons with energy around 0.5 MeV. Measuring these photons with the latest quantum technologies allows clear signatures (or witness) of quantum entanglement to be extracted, with a step change in precision and statistics compared to conventional technologies. The quantum-entanglement of the photons results in the "spooky" (according to Einstein!) action at a distance effects - measurement of an observable for one of the photons (e.g. its polarisation, location) instantaneously affects how the other interacts, even if they are well separated spatially. According to our current theories this connection never diminishes, extending out even to the size of the universe! However, although quantum-theory works incredibly well at the small scale (e.g atoms, nuclei, particles) we know it is incomplete (e.g. it doesn't include gravity) so establishing the validity of the quantum-theory to describe entanglement at large scales with new levels of precision, at increasing distance, over large numbers of gamma wavelengths, in accelerating frames (gravity is equivalent to acceleration in Einstein's general theory of relativity), at higher photon energies, in moving frames (with Einstein's special relativity), and at reducing wavepacket size are all important and fundamental tests. The consortium will provide groundbreaking new data obtained with the latest detector quantum-technologies, cutting edge plasma accelerator methods and a dataset from one of the world's most intense particle beam facilities. The data will be interpreted with the first implementation of MeV-scale entanglement into simulation.

Furthermore, alongside the pure science, applications enabled by a new level of understanding of MeV-scale entanglement have many exciting potential benefits to society. For example, if you have a Positron Emission Tomography (PET) at a hospital the detected gamma photons are quantum entangled, but we are only just learning of the benefits and impacts of this additional information. Our work will deliver the key data to guide future development of higher quality and more cost effective scanners. MeV-scale photons have the very useful ability to travel through large amounts of material and the benefits of entanglement are unexplored. Our developments of MeV-scale entanglement may have important implications for new security scanning devices e.g. at ports and airports. The role of entanglement in next generation compact laser-plasma particle accelerators will also be established, technologies which have tremendous potential in future medical treatments as well as a potential technology for next-generation particle accelerators for pure science.