A new view on spin reduced density matrix for relativistic particles

Abstract

We present a new interpretation for reduced density matrices of secondary variables in relativistic systems via an analysis of Wigner's method to construct the irreducible unitary representations of the Poincaré group. We argue that the usual partial trace method used to obtain spin reduced matrices is not fully rigorous, however, employing our interpretation, similar effective reduced density matrices can be constructed. In addition, we show that our proposal is more useful than the usual one since we are not restricted only to the reduced density matrices that could be obtained by the ordinary partial trace method.

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Cited by in corpus (9)

• Bell-type inequalities for systems of relativistic vector bosons
• Relativistic massive particle with spin-1/2, a vector bundle point of view
• Relativistic Einstein-Podolsky-Rosen correlations and localization
• Is bound entanglement Lorentz invariant?
• Relativistic spin operator must be intrinsic
• Observer dependence of entanglement in "nonrelativistic" quantum mechanics
• Lorentz transformations for massive two-particle systems: entanglement change and invariant subspaces
• Localization POVMs and intrinsic temporal uncertainty
• Bundle Theoretic Descriptions of Massive Single-Particle State Spaces; With a view toward Relativistic Quantum Information Theory