Quantum physics (QP) changed our worldview, it brought us modern electronic devices, and its almost mythical image fascinates. Although QP is relatively new in secondary education, it is now part of the national curricula of many countries. To understand the current state of QP content in high schools, we scrutinised upper secondary school physics curriculum documents in 15 countries. In these countries, we identified a similar core curriculum of QP which contains the following seven main categories: discrete atomic energy levels, interactions between light and matter, wave-particle duality, de Broglie wavelength, technical applications, Heisenberg's uncertainty principle, and the probabilistic nature of QP. We also found differences in the...