In this project we explore the relation between the whole and the part in quantum description of Nature. We approach it via two opposite perspectives, both benefiting from the achievements of quantum information theory: (i) On one hand the whole is the quantum world, and the parts – its subsystems, as well as emerging objective physical quantities, i.e. the quantities identically perceived by multiple observations. (ii) On the other hand, we aim to reconstruct the quantum mechanical description of the whole from assumptions on the total-system-vs-subsystems relations on the ground of general probabilistic theories (so called postquantum ones). (iii) Finally, we hope to merge the approaches and form a triangle Postquantum-Quantum-Objective by analyzing the link Postquantum-Objective.
To address the above questions, we will, in particular, (i) investigate general dynamical and kinematical mechanisms of emergence of objectivity and related phenomena; (ii) seek for multipartite constraints that augmented with local quantum description lead to quantum description of the whole. Finally, we will explore interaction between our questions and front-line of research such quantum thermodynamics, randomness amplification, and quantum many-body theory.