Experimental refutation of real-valued quantum mechanics under strict locality conditions

Abstract

Physicists describe nature using mathematics as the natural language, and for quantum mechanics, it prefers to use complex numbers. However, whether complex numbers are really necessary for the theory has been debated ever since its birth. Recently, it has been shown that a three-party correlation created in entanglement swapping scenarios comprising independent states and measurements cannot be reproduced using only real numbers. Previous experiments have conceptually supported the predication, yet not satisfying the independent state preparations and measurements simultaneously. Here, we implement such a test with two truly independent sources delivering entangled photons to three parties under strict locality conditions. By employing fast quantum random number generators and high-speed polarization measurements, we space-like separate all relevant events to ensure independent state preparations and measurements, and close locality loopholes simultaneously. Our results violate the real number bound of 7.66 by 5.30 standard deviations, hence rejecting the universal validity of the real-valued quantum mechanics to describe nature.

mian: 6 pages, 4 figures; supplementary: 7 pages, 5 figures

References in corpus (6)

• Quantum theory based on real numbers can be experimentally falsified
• 68 Gbps quantum random number generation by measuring laser phase fluctuations
• Testing real quantum theory in an optical quantum network
• Ruling out real-valued standard formalism of quantum theory
• Simulating quantum systems using real Hilbert spaces
• Efficiency of higher dimensional Hilbert spaces for the violation of Bell inequalities

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• Analyzing the free states of one quantum resource theory as resource states of another
• The detection power of real entanglement witnesses under local unitary equivalence
• Testing the necessity of complex numbers in traditional quantum theory with quantum computers
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• Generalized imaginary units in quantum mechanics
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• Experimental certification of the nonlocal advantages of quantum imaginarity