Experimentally Robust Self-testing for Bipartite and Tripartite Entangled States

TL;DR

This paper experimentally verifies robust self-testing bounds for bipartite and tripartite entangled states, demonstrating their validity across various states and significantly improving previous robustness results.

Contribution

The work provides experimental validation of recently predicted analytic self-testing bounds for bipartite and tripartite entangled states, enhancing their practical robustness.

Findings

Bounds are valid for various prepared entangled states.

Implemented robust self-testing processes with significant improvements.

Experimental results support theoretical predictions.

Abstract

Self-testing refers to a method with which a classical user can certify the state and measurements of quantum systems in a device-independent way. Especially, the self-testing of entangled states is of great importance in quantum information process. A comprehensible example is that violating the CHSH inequality maximally necessarily implies the bipartite shares a singlet. One essential question in self-testing is that, when one observes a non-maximum violation, how close is the tested state to the target state (which maximally violates certain Bell inequality)? The answer to this question describes the robustness of the used self-testing criterion, which is highly important in a practical sense. Recently, J. Kaniewski predicts two analytic self-testing bounds for bipartite and tripartite systems. In this work, we experimentally investigate these two bounds with high quality two-qubit and three-qubit entanglement sources. The results show that these bounds are valid for various of entangled states we prepared, and thus, we implement robust self-testing processes which improve the previous results significantly.