# Experimental device-independent certified randomness generation with an instrumental causal structure

## TL;DR

This paper demonstrates a new method for generating certified quantum randomness using an instrumental causal structure, combining theoretical proofs with experimental implementation, and showing advantages over traditional Bell-based protocols under low noise conditions.

## Contribution

It introduces a novel device-independent randomness generation protocol based on the instrumental scenario and experimentally validates it with entangled photons.

## Key findings

- Certified randomness can be extracted using instrumental-inequality violations.
- The protocol outperforms Bell-based protocols at low noise levels.
- Experimental implementation confirms theoretical predictions.

## Abstract

The intrinsic random nature of quantum physics offers novel tools for the generation of random numbers, a central challenge for a plethora of fields. Bell non-local correlations obtained by measurements on entangled states allow for the generation of bit strings whose randomness is guaranteed in a device-independent manner, i.e. without assumptions on the measurement and state-generation devices. Here, we generate this strong form of certified randomness on a new platform: the so-called instrumental scenario, which is central to the field of causal inference. First, we theoretically show that certified random bits, private against general quantum adversaries, can be extracted exploiting device-independent quantum instrumental-inequality violations. To that end, we adapt techniques previously developed for the Bell scenario. Then, we experimentally implement the corresponding randomness-generation protocol using entangled photons and active feed-forward of information. Moreover, we show that, for low levels of noise, our protocol offers an advantage over the simplest Bell-nonlocality protocol based on the Clauser-Horn-Shimony-Holt inequality.