Excluded states in entangled systems: technical and conceptual aspects

TL;DR

This paper explores the limitations and extensions of Pauli's exclusion principle in entangled quantum systems, analyzing how entanglement strength affects the principle's applicability and the nature of quantum states.

Contribution

It provides a detailed analysis of the conceptual and physical aspects of exclusion principles in entangled systems, highlighting differences between weak and strong entanglement regimes.

Findings

In weak entanglement, Pauli's principle can be approximately applied.

Atomic quantum numbers are multi-particle properties, not single-electron.

Strong entanglement leads to states independent of the exclusion principle.

Abstract

The impossibility of ascribing definite states to the constituents of an entangled system restricts the scope of Pauli's principle in this context. We analyze the conceptual and physical aspects of the problem by studying the actual scope of the principle and the possibility of extending the concept of exclusion in correlated systems. When the entanglement is weak, as in the archetypical case of the Helium atom, the principle can be applied in an approximated way. The concept of non-complete set of properties plays a crucial role in the argument, which also clarifies the physical meaning of the atomic quantum numbers; they are a multi-particle property, not an one-electron one. In contrast, for strong entanglement the excluded states are independent of the principle. We describe some of these states, many times determined by symmetries of the multi-fermion state.