Robust Self Testing of Unknown Quantum Systems into Any Entangled Two-Qubit States

TL;DR

This paper presents a robust method for self testing any pure entangled two-qubit state using Bell inequalities, enabling device-independent verification without prior assumptions on system dimension.

Contribution

It introduces a universal, robust self testing protocol for all pure two-qubit entangled states based on a single Bell inequality family.

Findings

Successfully self tests all pure two-qubit entangled states

Method is robust against experimental errors

Applicable to higher-dimensional bipartite states

Abstract

Self testing is a device independent approach to estimate the state and measurement operators, without the need to assume the dimension of our quantum system. In this paper, we show that one can self test black boxes into any pure entangled two-qubit state, by performing simple Bell type experiments. The approach makes use of only one family of two-inputs/two-outputs Bell inequalities. Furthermore, we outline the sufficient conditions for one to self test any dimensional bipartite entangled state. All these methods are robust to small but inevitable experimental errors.