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Relative subsystems and quantum reference frame transformations

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arxiv 2110.13199 v2 pith:FAIP73CC submitted 2021-10-25 quant-ph gr-qc

classification quant-phgr-qc
keywords quantumreferencetransformationsframeonlyframesframeworkgroup
verification ladder T0 review T1 audit T2 compute T3 formal
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Recently there has been much effort in developing a quantum generalisation of reference frame transformations. Despite important progress, a complete understanding of their principles is still lacking. In particular, we argue that previous proposals could yield reversible transformations between arbitrary quantum reference frames only when applied to the whole universe. In contrast, here we derive quantum reference frame transformations from first principles, using only standard quantum theory. Our framework, naturally based on incoherent rather than coherent group averaging, yields reversible transformations that only depend on the reference frames and system of interest. We find more general transformations than those studied so far, which are valid only in a restricted subspace. Importantly, our framework contains additional degrees of freedom in the form of an "extra particle," which carries information about the quantum features of reference frame states. Our formalism is valid for a broad range of symmetry groups. We study the centrally extended Galilei group specifically, highlighting key differences from previous proposals.

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Cited by 10 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Quantum reference frames beyond subsystems: a reconstruction and generalization of the perspective-neutral framework

    quant-ph 2026-07 accept novelty 7.5 of 10

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