Foundations of Physics

, Volume 44, Issue 7, pp 709–724 | Cite as

On the Identification of the Parts of Compound Quantum Objects

  • Gregg Jaeger


A view of the constitution of quantum objects as reducible, in the sense of being decomposable to elementary particles, is outlined. On this view, parts of composite quantum systems are considered to be identified according to a recently introduced, specifically quantum notion of individuation (Jaeger, Found Phys 40:1396 2010). These parts can typically also be considered particles according to Wigner’s symmetry-based notion. Particles are considered elementary when they satisfy a condition of elementarity, newly introduced here, that improves on that provided by Newton and Wigner. In any given instance, the compound character of a physical object can be verified in principle by decomposition, ultimately to a set of such elementary parts, through appropriate precise quantum measurements during experimentation consistently with this principle of individuation.


Quantum theory Reduction Composite system Object Particle 



This research was supported by the DARPA QUINESS program through U.S. Army Research Office Award No. W31P4Q-12-1-0015. I would also like to thank Brigitte Falkenburg for helpful comments.


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© Springer Science+Business Media New York 2014

Authors and Affiliations

  1. 1.Quantum Communication and Measurement Laboratory, Department of Electrical and Computer Engineering and Division of Natural Science and MathematicsBoston UniversityBostonUSA

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