Position Measurements Obeying Momentum Conservation
arXiv:1005.0569 · doi:10.1103/PhysRevLett.106.110406
Abstract
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 (WAY) theorem, and shows that accurate position measurements are only practically feasible if there is a large momentum uncertainty in the apparatus.