Loophole-free Bell test using electron spins in diamond: second experiment and additional analysis

Area of Science:

• Quantum Physics
• Experimental Physics

Background:

• Bell's inequality violation provides loophole-free evidence against local-realist theories.
• Previous experiments have demonstrated such violations using entangled electronic spins in diamonds.

Purpose of the Study:

• To report on data from a second Bell experiment using a similar setup.
• To further validate the violation of Bell inequalities and test local-realist theories.
• To analyze the robustness of the experimental results against potential loopholes.

Main Methods:

• Conducting a second Bell experiment with entangled electronic spins in diamonds.
• Measuring the violation of the CHSH-Bell inequality.
• Analyzing settings choices and random number generator (RNG) imperfections.

Main Results:

• A violation of the CHSH-Bell inequality of 2.35 ± 0.18 was observed in the second experiment.
• The combined results from both experiments yielded an overall S value of 2.38 ± 0.14.
• The experimental results were found to be robust against RNG bias, even with early random bit generation.

Conclusions:

• The second Bell experiment independently confirms the violation of Bell inequalities.
• The combined results strengthen the evidence against local-realist theories.
• The study demonstrates the resilience of the experimental findings to potential systematic errors.