Fundamental bounds in realistic quantum enhaced metrology found
by: R. Demkowicz-Dobrzanski, J. Kolodynski, M. Guta
Entanglement is a unique quantum feature that allows for a number of spectacular applications such as quantum teleportation, quantum cryptography or quantum computing. It has been also proposed that appropriately prepared entangled states may enhance substantially the precision of some of the most spectacular measuring devices operating nowadays such as atomic clocks or gravitational wave detectors. This ideas found their way in a rapidly developing field of quantum enhanced metrology. Until very recently it had not been known, however, to what extent quantum metrology is robust to real-life imperfections such as light attenuation, loss of atoms and environmental noise. Fundamental bounds on maximal possible quantum enhancement that can be achieved in quantum metrological protocols operating in realistic environments have been derived. The derived bounds allow to understand the regime where quantum entanglement is helpful in boosting measurement precision and set a benchmark for experimental implementations of quantum enhanced protocols. In particular it has been shown that the quantum enhancement obtained recently in the GEO600 gravitational wave observatory using squeezed vacuum states is operating very close to the fundamental bound.
Workpackage: wp-1.1: Quantum metrology in real-world environments
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