Certification of multi-qubit quantum systems with temporal inequalities

Abstract Demonstrating contextual correlations in quantum theory through the violation of a non-contextuality inequality necessarily needs some ‘contexts’ and thus assumes some compatibility relations between the measurements. As a result, any self-testing protocol based on the maximal violation of such inequality is not free from such assumptions. In this work, we propose temporal inequalities derived from non-contextuality inequalities for multi-qubit systems without assuming any compatibility relations among the measurements. We demonstrate that the new inequalities can be maximally violated via a sequential measurement scenario. Moreover, using the maximal violation of these temporal inequalities, we are able to certify the multi-qubit Greenberger–Horne–Zeilinger (GHZ) states and the measurements.