Interferometry, Quantum Measurements and Cavity QED with Atoms

Herman C. W. Beijerinck, K. A. H. van Leeuwen

Thomas Bourdel, Tobias Donner, Stephan Ritter +3 more

We observe the build-up of a matter wave interference pattern from single atom detection events in a double-slit experiment. The interference arises from two overlapping atom laser beams extracted from a rubidium Bose-Einstein condensate. Our detector is a high-finesse optical cavity which realizes a quantum measurement of the presence of an atom and thereby projects delocalized atoms into a state with zero or one atom in the resonator. The experiment reveals simultaneously the granular and the wave nature of matter. We present a setup which is suited for applications in atom interferometry and cavity QED.

Monika A. M. Marte, P. Zoller, Murray Holland +2 more

Sylvester Amoah, Kishore T. Kapale

We propose a cavity QED based sequential N-atom GHZ state generator. As GHZ states can be easily converted to path-entangled N00N states, this would open new pathways for Heisenberg-limited atom interferometry.

Karol Gietka, Tomasz Wasak, Jan Chwedeńczuk +2 more

We propose an enhanced optical interferometer based on tailored non-classical light generated by nonlinear dynamics and projective measurements in a three-level atom cavity QED system. A coherent state in the cavity becomes dynamically entangled with two ground states of the atom and is transformed to a macroscopic superposition state via a projective measurement on the atom. We show that the resulting highly non-classical state can improve interferometric precision measurements well beyond the shot-noise limit once combined with a classical laser pulse at the input of a Mach–Zehnder interferometer. For a practical implementation, we identify an efficient phase shift estimation scheme based on the counting of photons at the interferometer output. Photon losses and photon-counting errors deteriorate the interferometer sensitivity, but we demonstrate that it still can be significantly better than the shot-noise limit under realistic conditions.

Daniel F. Walls, Sze Tan, Pippa Storey +1 more