Position Measurements Obeying Momentum Conservation

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We present a hitherto unknown fundamental limitation to a basic measurement: that of the position of a quantum object when the total momentum of the object and apparatus is conserved. This result extends the famous Wigner-Araki-Yanase theorem, and shows that accurate position measurements are only practically feasible if there is a large momentum uncertainty in the apparatus.
Original languageEnglish
Article number110406
Pages (from-to)1-4
Number of pages4
JournalPhysical Review Letters
Issue number11
Publication statusPublished - 18 Mar 2011


  • Mathematical Physics

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