Single Ion Thermal Wave Packet Analyzed Via Time-Of-Flight Detection

TL;DR

This paper demonstrates a method to analyze and infer the motional state of a single trapped ion by engineering its extraction and measuring its time-of-flight, enabling remote sensing of quantum wave packets.

Contribution

It introduces a technique combining wave packet engineering, trajectory modeling, and time-of-flight detection to analyze the motional state of a single ion outside the trap.

Findings

Successfully inferred the ion's motional excitation state.

Achieved precise remote sensing of quantum wave packets.

Demonstrated control over ion extraction and detection processes.

Abstract

A single $^{40}$Ca ion is confine in the harmonic potential of a Paul trap and cooled to a temperature of a few mK, with a wave packet of sub-m spatial and sub-m/s velocity uncertainty. Deterministically extracted from the Paul trap, the single ion is propagating over a distance of 0.27 m and detected. By engineering the ion extraction process on the initial wave packet, theoretically modeling the ion trajectories, and studying experimentally the time-of-flight distribution, we directly infer the state of the previously trapped ion. This analysis allows for accurate remote sensing of the previous motional excitation in the trap potential, both coherently or incoherently. Our method paves a way to extract, manipulate and design quantum wave packets also outside of the Paul trap.