# Experimental demonstration of measurement-device-independent measure of quantum steering

## TL;DR

This paper introduces and experimentally demonstrates a measurement-device-independent measure of quantum steering, which relies solely on observed statistics and quantum inputs, and is robust against measurement biases and losses.

## Contribution

The paper presents a new MDI measure of quantum steerability, proves its properties, and experimentally estimates it using entangled photons, advancing one-sided device-independent quantum information processing.

## Key findings

- Successfully estimated the steerability measure experimentally.
- Provided lower bounds on entanglement and measurement incompatibility.
- Demonstrated robustness against measurement biases and losses.

## Abstract

Within the framework of quantum refereed steering games, quantum steerability can be certified without any assumption on the underlying state nor the measurements involved. Such a scheme is termed the measurement-device-independent (MDI) scenario. Here we introduce a measure of steerability in an MDI scenario, i.e., the result merely depends on the observed statistics and the quantum inputs. We prove that such a measure satisfies the convex steering monotone. Moreover, it is robust against not only measurement biases but also losses. We also experimentally estimate the amount of the measure with an entangled photon source. As two by-products, our experimental results provide lower bounds on an entanglement measure of the underlying state and an incompatible measure of the involved measurement. Our research paves a way for exploring one-side device-independent quantum information processing within an MDI framework.