Trapped-Ion State Detection through Coherent Motion

TL;DR

This paper introduces a versatile method for detecting the quantum state of trapped ions by coupling them to a control ion and measuring induced coherent motion, applicable to various atomic and molecular species.

Contribution

It presents a novel technique for ion state detection using off-resonant laser excitation and coherent motion measurement, avoiding ground state cooling and reducing spontaneous emission.

Findings

Successfully distinguished Al+ clock states without ground state cooling.

Demonstrated nondestructive Zeeman sublevel detection in Al+ ground state.

Implemented two measurement methods: photon counting and sideband excitation.

Abstract

We demonstrate a general method for state detection of trapped ions that can be applied to a large class of atomic and molecular species. We couple a "spectroscopy" ion (Al+) to a "control" ion (Mg+) in the same trap and perform state detection through off-resonant laser excitation of the spectroscopy ion that induces coherent motion. The motional amplitude, dependent on the spectroscopy ion state, is measured either by time-resolved photon counting, or by resolved sideband excitations on the control ion. The first method provides a simplified way to distinguish "clock" states in Al+, which avoids ground state cooling and sideband transitions. The second method reduces spontaneous emission and optical pumping on the spectroscopy ion, which we demonstrate by nondestructively distinguishing Zeeman sublevels in the 1S0 ground state of Al+.