Motional state analysis of a trapped ion by ultra-narrowband composite pulses

TL;DR

This paper introduces a novel method using ultra-narrowband composite pulses to measure the motional states of a trapped ion, effective across different regimes and capable of filtering phonon number ranges.

Contribution

It presents a new technique for motional state measurement that does not require prior knowledge and is easily implementable in various regimes.

Findings

Successful demonstration with a single trapped ion

Good detection results with numerical evaluation

Effective filtering of phonon number ranges

Abstract

In this work, we present a method for measuring the motional state of a two-level system coupled to a harmonic oscillator. Our technique uses ultra-narrowband composite pulses on the blue sideband transition to scan through the populations of the different motional states. Our approach does not assume any previous knowledge of the motional state distribution and is easily implemented. It is applicable both inside and outside of the Lamb-Dicke regime. For higher phonon numbers especially, the composite pulse sequence can be used as a filter for measuring phonon number ranges. We demonstrate this measurement technique using a single trapped ion and show good detection results with the numerically evaluated pulse sequence.