Quantum Measurement with Entangled Atoms

摘要

We investigate, theoretically and experimentally, methods to generate quantum mechanically entangled states of ensembles of atomic particles. The theoretical goals are: determine the best entangled states for particular applications and devise ways to generate these states and ways to measure them. The experimental goals are: demonstrate the increase in signal-to-noise ratio in spectroscopy using entangled particles, and find effective means to create the desired entangled states for particular measurements. We have created entangled states of two and four trapped (9)Be(+) ions in a single-step, deterministic way. These states are those desired for spectroscopy with higher signal-to-noise ratio than possible with unentangled atoms. The procedure can be scaled to large numbers of ions. We have identified causes of imperfect fidelity and are taking actions to eliminate these causes.