| （英） |
In the theory of quantum fields or quantum many-body systems, a vacuum state is a fundamental one. The vacuum state of a quantum field or many-body system has quantum entanglement, and it has been known that its entanglement are important not only for field theory and condensed matter theory, but also for cosmology and gravitational physics. To understand how local observers measure the quantum nonlocality, in this research we discuss the detection of quantum nonlocality for a vacuum state by two spin detectors. As a simple model, we consider the vacuum of a massless scalar field and the interaction with the two spin detectors, and solve its time evolution perturbatively. From the obtained state of the two spins, we evaluate the quantum entanglement and the violation of the Bell's inequality between the detectors. We find that the detected quantum nonlocality strongly depends on the initial condition of the detectors, which tells us what experiment to extract the nonlocality are suitable.
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