Symmetry packaging I: Irreducible representation blocks, superselection, and packaged entanglement in quantum field theory

Abstract

We introduce the concept of symmetry packaging for quantum field excitations: in a quantum field theory with a gauge group G, every local creation operator carries its full set of internal quantum numbers (IQNs) as a single irreducible G-block and forbids any partial factorization. We elevate this observation to a symmetry packaging principle, which asserts that packets of IQNs remain intact throughout all physical processes. We analyze a quantum-field excitation in six successive stages: (1) particle creation/annihilation, (2) hybridization with gauge-blind external degrees of freedom (DOFs), (3) tensor-product assembly, (4) isotypic decomposition, (5) packaged superposition/entanglement, and (6) local Gauge-Invariance constraint. We show that packaging survives every stage and culminates in a gauge-invariant physical Hilbert space. These stages unfold within a three packaging layer hierarchy (raw-Fock → isotypic → physical) with distinct packaging characters. Packaging alone reproduces familiar charge-superselection rules and, within any fixed-charge sector, admits a new class of packaged entangled states where internal and external DOFs are inseparably locked. We derive necessary and sufficient conditions for such superpositions and show that packaged irreps behave as noise-protected logical qudits. This framework unifies representation theory, superselection, and entanglement under a single mathematical roof and provides a roadmap for constructing and manipulating packaged states in any gauge theory.