Homogeneous Atom-Cavity Coupling for Quantum Metrology

Interactions between cold atoms and optical cavities have been proved successful in generating large amounts of spin-squeezing. However, the inhomogeneous coupling between the atoms and optical cavity, due to the standing wave nature of the cavity modes and the incommensurateness between the trapping and probing light, can limit the applications of spin-squeezed states. In this thesis, I will summarize our efforts towards creating homogeneous atom-cavity coupling, and attempts at utilizing spin-squeezed states in which the entanglement is more evenly distributed among all the atoms for quantum metrology. I demonstrate a method to obtain more homogeneous atom-cavity coupling in the Lamb-Dicke regime by initially loading atoms into thousands of lattice sites and then using a spectroscopic method to select and keep only those atoms at lattice sites with near maximal coupling to the desired cavity mode. The degree of residual inhomogeneity is expected to reduce quadratically with the number of the retained atoms. We are able to select 4% of the atoms and get an average coupling strength of more than 91% the peak coupling strength. I present an ongoing project to build an intracavity, guided atom interferometer with spin-squeezed states. Spin-squeezing homogeneously distributed between all the atoms are required, which will be realized by time-averaged probing of falling atoms, in the non-Lamb-Dicke regime. I will give a detailed account about how all the ingredients for the squeezed atom interferometry are realized and and a brief summary of our recent progress. I will also talk about a novel cooling method utilizing adiabatic transfer on Raman transitions, and introduce a proposal for continuous real-time tracking of a quantum phase and the creation of spin-squeezed states in the quantum phase quadrature.