# Implementation of quantum state tomography for time-bin qudits

## TL;DR

This paper introduces a quantum state tomography method tailored for time-bin qudits, enabling efficient reconstruction of high-dimensional entangled states with fewer measurement settings, demonstrated on a four-dimensional system.

## Contribution

The paper presents a novel QST scheme for time-bin qudits with measurement settings scaling linearly with dimension, improving efficiency over previous methods.

## Key findings

- Successfully reconstructed a four-dimensional entangled state with 16 measurement settings.
- Achieved an average fidelity of 0.950 in state reconstruction.
- Demonstrated the practicality of the method for high-dimensional quantum systems.

## Abstract

Quantum state tomography (QST) is an essential tool for characterizing an unknown quantum state. Recently, QST has been performed for entangled qudits based on orbital angular momentum, time-energy uncertainty, and frequency bins. Here, we propose a QST for time-bin qudits, with which the number of measurement settings scales linearly with dimension $d$. Using the proposed scheme, we performed QST for a four-dimensional time-bin maximally entangled state with 16 measurement settings. We successfully reconstructed the density matrix of the entangled qudits, with which the average fidelity of the state was calculated to be 0.950.