# Experimentally Self-Testing Partially Entangled Two-Qubit States on an Optical Platform

## TL;DR

This paper presents a new method to test partially entangled two-qubit states without full reconstruction, using an optical setup.

## Contribution

A self-testing protocol for non-maximally entangled states under black-box assumptions is experimentally validated.

## Key findings

- A complete self-testing protocol for two-qubit partially entangled states is implemented.
- High-fidelity self-testing is achieved using polarization-entangled photons in a free-space optical setup.
- The method supports device-independent quantum information processing applications.

## Abstract

We demonstrate a complete and experimentally validated self-testing protocol for two-qubit partially entangled states, which avoids the need for full tomographic reconstruction. Using a room-temperature type-II PPKTP polarization-entangled source and a free-space optical setup, we implement both quantum state tomography and optimal generalized Bell measurements within a single system. Our approach achieves high-fidelity self-testing of non-maximally entangled states under black-box assumptions, establishing a solid foundation for device-independent quantum information processing applications.