The Jagiellonian Positron Emission Tomograph (J-PET) is the first multi-photon PET scanner capable of measuring momentum vectors and polarization of photons originating from the decays of positronium.

J-PET enables imaging of positronium properties in living organisms, the study of matter-antimatter symmetries in positronium decays, and studies of the degree of quantum entanglement of photons from electron-positron annihilations.

We will present the first-ever images of the properties of positronium in humans [1,2,3], the first multi-photon images from decays of positronium atoms into three photons [4,5], and the first observation of non-maximal entanglement of photons from positronium annihilation in matter [6]. 

We will also discuss the status of development of (i) positronium and (ii) degree of quantum entanglement as possible diagnostic biomarkers.

[1] P. Moskal et al., Nature Reviews Physics 1, 527 (2019).

[2] P. Moskal et al., Science Advances 7, eabh4394 (2021).

[3] P. Moskal et al., Science Advances 10, eadp2890 (2024).

[4] P. Moskal et al., Nature Communication 12, 5658 (2021).

[5] P. Moskal et al., Nature Communication 15, 79 (2024).

[6] P. Moskal et al., Science Advances11 (2025) eads3046, in review