Approximating relational observables by absolute quantities: a quantum accuracy-size trade-off

Paul Busch, Leon Deryck Loveridge, Takayuki Miyadera

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The notion that any physical quantity is defined and measured relative to a reference frame is traditionally not explicitly reflected in the theoretical description of physical experiments where, instead, the relevant observables are typically represented as 'absolute' quantities. However, the emergence of the resource theory of quantum reference frames as a new branch of quantum information science in recent years has highlighted the need to identify the physical conditions under which a quantum system can serve as a good reference. Here we investigate the conditions under which, in quantum theory, an account in terms of absolute quantities can provide a good approximation of relative quantities. We find that this requires the reference system to be large in a suitable sense.
Original languageEnglish
Article number185301
Number of pages17
JournalJournal of Physics A: Mathematical and Theoretical
Issue number18
Publication statusPublished - 22 Mar 2016

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  • quantum mechanics
  • quantum reference frame

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