Beijing Institute of Mathematical Sciences and Applications

Yu Wang

Tianfeng Feng

Friday, September 8, 2023 10:30 AM - 11:30 AM

A3-2-301

Understanding gravity in the framework of quantum mechanics is one of the great challenges in modern physics. Recently, a quantum-information-theoretic approach to testing quantum gravity which suggests that the observation of gravitationally induced entanglement between two massive particles is the evidence for its quantum nature. So far, various physical systems have been suggested, such as Stern-Gerlach interferometry, neutrino-like oscillations, optomechanics and atomic interferometers. However, quantum effects in the gravitational field are exceptionally small so that the existing quantum-gravity proposals seem extremely challenging. For addressing the key challenge mentioned above, in this talk, we will present a criterion based on the logical contradictions of weak entanglement, which can boost the sensitivity of the signal due to the gravitationally induced entanglement. Specifically, we make use of both the weak-value scenario and the Einstein-Podolsky-Rosen (EPR) steering. Similarly to the Bell test, we consider two sets of measurement bases that can be randomly selected, one of which is the normal measurement basis (e.g., the computational basis) while the other one corresponds to weak value amplification. We show that in the case of weak entanglement, the classical mediator (in this case, the gravitational field) cannot simulate the results related to the measurement visibility of weak-value basis, thus ruling out the separable model. Compared to the previous protocols, our approach can amplify the quantum signal of gravity by any desired factor that depends on the magnitude of the weak value. That is, our approach may allow us to observe entangled signals that were previously impossible to observe. Our work makes the detection of gravitationally mediated entanglement much closer to experimental realization and also pave the way for weak entanglement criterion of a more general nature.

Tianfeng Feng is a postdoctoral fellow at the University of Hong Kong. He focuses on theories and experiments related to quantum information processing and quantum foundations, and has published more than 10 papers in high-impact journals, including Phys. Rev. D, npj Quantum Information, Photonics Research, Phys. Rev. A, etc.