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.

arXiv commentmian: 6 pages, 4 figures; supplementary: 7 pages, 5 figures

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• Resource Theory of Imaginarity: New Distributed Scenarios
• Certification of non-classicality in all links of a photonic star network without assuming quantum mechanics
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• Experimental nonclassicality in a causal network without assuming freedom of choice
• Experimental demonstration of genuine tripartite nonlocality under strict locality conditions
• Quantifying imaginarity in terms of pure-state imaginarity
• Proposals for ruling out the real quantum theories in an entanglement-swapping quantum network with causally independent sources
• Expectation value dynamics within real Hilbert space quantum mechanics
• Efficient discrimination between real and complex quantum theories
• Two imaginarity monotones induced by unified $(\alpha ,\beta )$-relative entropy
• Quantum-imaginarity-based quantum speed limit
• Quantum mechanics based on real numbers: A consistent description
• Partial independence suffices to rule out Real Quantum Theory experimentally
• A universal scheme to self-test any quantum state or measurement
• Coherence and Imaginarity as Resources in Quantum Circuit Complexity
• Memory attacks in network nonlocality and self-testing
• Self-interacting quantum particles and the Dirac delta potential
• Quantifying imaginarity of quantum operations
• Imaginarity measures induced by real part states and the complementarity relations
• Klein-Gordon equation within the real Hilbert space formalism
• 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
• Faithful real embedding of a three-dimensional complex Kochen-Specker configuration
• Generalized imaginary units in quantum mechanics
• Deformed angular momentum algebra within the real Hilbert space
• Experimental certification of the nonlocal advantages of quantum imaginarity