Loophole-free bell test for continuous variables via wave and particle correlations

Area of Science:

• Quantum Information Science
• Quantum Foundations
• Quantum Optics

Background:

• Local realism, a cornerstone of classical physics, is challenged by quantum mechanics.
• Bell inequalities provide a framework to experimentally test local realism against quantum mechanics.
• The Peres conjecture relates entanglement criteria to Bell inequality violations.

Purpose of the Study:

• To derive novel multimode Bell inequalities verifiable under local realistic assumptions.
• To investigate the violation of these inequalities by entangled states, specifically those negative under partial transposition.
• To demonstrate the potential for loophole-free experimental tests of quantum mechanics.

Main Methods:

• Derivation of two classes of multimode Bell inequalities.
• Utilizing wave and particle correlations from continuous-variable quantum states.
• Analysis of inequality violation concerning detector efficiency.

Main Results:

• The derived inequalities are violated exclusively by entangled states that are negative under partial transposition, confirming the Peres conjecture.
• Demonstrated significant violations of the inequalities using readily accessible continuous-variable states.
• The inequalities exhibit robustness against detector inefficiencies, a key factor for loophole-free tests.

Conclusions:

• The study provides a practical method for testing the failure of local realism.
• The findings strongly support the feasibility of loophole-free experimental verification of quantum entanglement.
• The work validates the connection between entanglement criteria and Bell inequality violations.