# Experimental investigation of partially entangled states for device-independent randomness generation and self-testing protocols

## TL;DR

This experimental study investigates the practicality of using partially entangled photonic qubits for device-independent randomness generation and self-testing, highlighting limitations with low entanglement.

## Contribution

It provides empirical evidence on the challenges of using partially entangled states for device-independent tasks in realistic conditions.

## Key findings

- Low entangled states are less effective for self-testing.
- Practical limitations hinder randomness generation with small deviations from ideal states.
- Maximally entangled states remain the best candidates for device-independent protocols.

## Abstract

Previous theoretical works showed that all pure two-qubit entangled states can generate one bit of local randomness and can be self-tested through the violation of proper Bell inequalities. We report an experiment in which nearly pure partially entangled states of photonic qubits are produced to investigate these tasks in a practical scenario. We show that small deviations from the ideal situation make low entangled states impractical to self-testing and randomness generation using the available techniques. Our results show that in practice lower entanglement implies lower randomness generation, recovering the intuition that maximally entangled states are better candidates for deviceindependent quantum information processing.