General Quantum Hilbert Space Modeling Scheme for Entanglement
This work provides a theoretical framework for understanding entanglement in quantum systems, potentially impacting quantum information theory and foundational physics, though it appears incremental as it builds on existing quantum modeling concepts.
The authors developed a classification scheme for modeling composite quantum entities that violate Bell inequalities and exhibit entanglement, showing that entanglement is a joint property of states and measurements, and that entangled measurements can model situations previously thought to be 'beyond quantum', with extensions to quantum mixtures.
We work out a classification scheme for quantum modeling in Hilbert space of any kind of composite entity violating Bell's inequalities and exhibiting entanglement. Our theoretical framework includes situations with entangled states and product measurements ('customary quantum situation'), and also situations with both entangled states and entangled measurements ('nonlocal box situation', 'nonlocal non-marginal box situation'). We show that entanglement is structurally a joint property of states and measurements. Furthermore, entangled measurements enable quantum modeling of situations that are usually believed to be 'beyond quantum'. Our results are also extended from pure states to quantum mixtures.