SciPost Thesis Link
|Title:||Spin squeezing and non-linear atom interferometry with Bose-Einstein condensates|
|As Contributor:||(not claimed)|
|Degree granting institution:||University of Heidelberg|
|Supervisor(s):||Prof. M. Oberthaler|
Interferometry is the most precise measurement technique known today. It is based on interference and therefore on the wave-like nature of the resources, photons or atoms, in the interferometer. As given by the laws of quantum mechanics the granular, particle-like features of the individually independent atoms or photons are responsible for the precision limit, the shot noise limit. However this “classical” bound is not fundamental and it is the aim of quantum metrology to overcome it by employing quantum correlations, i.e. entanglement, among the particles. We report on the realization of spin squeezed states suitable for atom interferometry based on two external modes of a Bose-Einstein condensate. We detect many-body entangled states which allow, in principle, for a precision gain of 35% over the shot noise limit in atom interferometry. We demonstrate a novel non-linear atom interferometer for Bose-Einstein condensates whose linear analog, the Ramsey interferometer, is used for the definition of the time standard. Within the non-linear interferometer we detect a large entangled state of 170 inseparable atoms. A measurement with this interferometer outperforms its ideal linear analog by 15% in phase estimation precision showing directly the feasibility of non-linear atom interferometry with Bose-Einstein condensates beyond “classical” precision limits.