University of Science and Technology of China Guo Guangcan Academician Team has made important progress in basic research on Quantum mechanics . The team, Li Chuanfeng, Huang Yunfeng, and others, collaborated with Spanish theoretical physicist to experimentally verify the true multi-body non-locality under the theoretical framework of local operation and shared randomness (LOSR, Local operation and shared randomness). The results show that using two-body or three-body non-local associations cannot explain all the associations generated by nature. The result was published in the internationally renowned journal Physical Review Letters on October 4, and was selected as the cover article of the in this issue.
Figure 1: This issue's PRL cover
Quantum mechanics allows non-local associations between particles, that is, quantum non-locality. Quantum non-locality is an important resource for realizing various quantum information processes. For multibody systems, true multibody non-locality is considered to be the strongest non-local correlation that can be displayed in multibody systems. True multi-body non-locality tests usually rely on violations of inequalities under the framework of local operation and classical communication (LOCC, local operation and classical communication). However, in the multi-body non-locality test, we usually need to assume that the probability distribution , jointly measured between different observers, obeys the non-signaling condition, and classical communication is prohibited, so true multi-body non-locality based on LOCC is not a good definition.
Figure 2: (a) LOSR local model; (b) New LOSR inequality with white noise robustness.
In quantum resource theory, LOCC is not the only free operation that can be used to define entangled resources. After removing classic communication, a more natural definition is the theoretical framework based on LOSR. In the experiment, the research team first verified the non-locality of the three-body entangled structure. The LOSR local model of the trisomy system allows shared randomness between the trisomy bodies and allows no limits on the association between any two bodies, that is, the association can be a quantum association or a wider range of associations that do not rely on the description of quantum mechanics.
research group and Marc-Olivier Renou et al. improved the non-local inequality of LOSR proposed in previous relevant theoretical work, and proposed a more robust inequality for the common white noise in multi-photon experiments. In the experiment, the independent "sandwich-type" high-fidelity multi-photon entanglement source [PRL115, 260402 (2015)] was used to verify the non-locality of true three-body LOSR with a violation of 26.3 standard deviations. The research group further violated the true four-body LOSR inequality in the four-body situation. The experiment excluded a localized model based on shared randomness and generalized association of three-body, and demonstrated the true four-body non-locality. These experimental results show that only two-body or tribody non-local associations cannot explain all associations produced by nature. The inequality proposed in this work can be extended to any N-body situation, and the method of preparing high-fidelity entanglement sources lays the foundation for experimentally demonstrating the non-locality of a larger number of subsystems.
article co-first authors are doctoral student Cao Huan in the Key Laboratory of Quantum Information, Chinese Academy of Sciences, associate researcher Zhang Chao, and Marc-OlivierRenou from the Spanish Institute of Photonic Science. This work has been funded by the National Natural Science Foundation of China, the Chinese Academy of Sciences, and Anhui Province.
(Key Laboratory of Quantum Information, Chinese Academy of Sciences, Institute of Quantum Information and Quantum Science and Technology Innovation, School of Science and Technology, School of Physics, Department of Research)
Paper link:
html s://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.150402
--University of Science and Technology of China
