# Tracking the dynamics of an ideal quantum measurement

## TL;DR

This paper experimentally investigates whether natural processes can realize ideal quantum measurements, demonstrating through tomography that a trapped ion's measurement dynamics closely match the theoretical ideal with high fidelity.

## Contribution

It provides the first experimental evidence that a natural measurement process can behave as an ideal quantum measurement, confirming theoretical predictions.

## Key findings

- Measurement process develops as an ideal quantum measurement
- Average fidelity of 94% with the ideal model
- Monitoring of measurement dynamics via tomography

## Abstract

The existence of ideal quantum measurements is one of the fundamental predictions of quantum mechanics. In theory the measurement projects onto the eigenbasis of the measurement observable while preserving all coherences of degenerate eigenstates. The question arises whether there are dynamical processes in nature that correspond to such ideal quantum measurements. Here we address this question and present experimental results monitoring the dynamics of a naturally occurring measurement process: the coupling of a trapped ion qutrit to the photon environment. By taking tomographic snapshots during the detection process, we show with an average fidelity of $94\%$ that the process develops in agreement with the model of an ideal quantum measurement.