Robust and versatile black-box certification of quantum devices.

Area of Science:

• Quantum Information Science
• Quantum Computing
• Device Characterization

Background:

• Self-testing assesses quantum devices (states and measurements) in a black-box manner using observed statistics.
• Existing self-testing methods are limited to ideal quantum devices and lack robustness.

Purpose of the Study:

• To develop a more robust and versatile self-testing framework for quantum devices.
• To overcome limitations of previous self-testing schemes and enable assessment of imperfect devices.

Main Methods:

• Utilized the semidefinite programming hierarchy for characterizing quantum correlations.
• Applied this hierarchy to analyze quantum device performance and certify quantum states.

Main Results:

• Achieved dramatically improved robustness for self-testing schemes.
• Demonstrated that a Clauser-Horne-Shimony-Holt violation > 2.57 certifies a singlet fidelity > 70%.
• Enabled robust self-testing of nonmaximally entangled two-qutrit states.

Conclusions:

• The semidefinite programming hierarchy offers a powerful tool for advancing quantum device self-testing.
• This approach significantly enhances the reliability and scope of black-box quantum device assessment.