Experiments of China University of Science and Technology demonstrate the simultaneous guidance of quantum states in many-body systems
The team of Academician Guo Guangcan of USTC has recently made important progress in basic research on quantum information. The team Li Chuanfeng, Xu Jinshi, Sun Kai and others conducted experimental research on the relational structure of many-body quantum guidance, and for the first time observed the non-monologous sharing relationship of many-body quantum guidance, that is, the quantum state of one of the quantum states can be used by the other two. side guide at the same time. The research results were published in the internationally renowned physics journal "Physical Review Letters" on March 24.
Quantum steering describes the ability of one particle to influence the quantum state of another particle through local measurements. As a quantum non-local phenomenon, quantum steering has unique asymmetric properties, which can further realize single-vector quantum steering, that is, one side can guide the other side, but not vice versa. In the research of many-body quantum steering, the monogamous relationship will limit the sharing ability of quantum steering among individuals, so that one party cannot be guided by other parties at the same time. However, theoretical studies have shown that with increasing measurement directions, many-body quantum guides can violate monoligability, exhibiting a rich structure of guide-sharing relationships among many bodies. To experimentally verify this non-monologous sharing relationship, we need to be able to perform arbitrary measurements on many-body quantum systems, which requires us to prepare many-body entangled qubit systems with high fidelity.
Based on the optical platform, Li Chuanfeng, Xu Jinshi, Sun Kai and others have systematically carried out experimental research on quantum steering in recent years, including the verification of all-versus-nothing quantum steering [PRL 113, 140402 (2014)] , implementation of single-vector quantum guidance [PRL 116, 160404 (2016); PRL 118, 140404 (2017)], etc. In this work, the research group further utilized the three degrees of freedom of photon polarization, path and orbital angular momentum to construct a three-qubit system, and prepared a series of three-body entangled states with an average fidelity of 96%. The research group studied the non-monologous shared relationship of many-body quantum steering by extending the uncertainty relation criterion of quantum steering. The experimental results show that in a three-body quantum system, the quantum state of one side can be guided by the other two at the same time, which violates the traditional monotony relationship and confirms the shared nature of many-body quantum steering. The research group demonstrated different quantum steering architectures by fully analyzing the three-body system in the W state (a class of many-body entangled states). Using the confirmed shared relationship of many-body quantum-guided non-monologousness, the research group further realized the experimental verification of three-body true entanglement. Compared with conventional methods, this detection method requires less measurement resources, demonstrating its high efficiency.
Figure 1. Quantum steering structure in a three-body system. The non-crossed arrows indicate that one party can lead the other, and the crossed arrows indicate that one cannot lead the other. a. Quantum-guided monogamous relational structure. Neither party can be guided by the other two at the same time; b. The shared relationship structure that violates monogamy. One party can be directed by the other two at the same time.
This achievement demonstrates the rich relational structure of quantum steering in many-body systems, deepens the understanding of the physical concept of quantum steering, and has important implications for fundamental research on quantum information. At the same time, this work provides a comprehensive analysis perspective for information protocols based on quantum-guided monogamy, and has important application prospects in multi-user quantum communication, quantum network construction, and multi-body entanglement detection.
Hao Zeyan, a doctoral student at the Key Laboratory of Quantum Information, Chinese Academy of Sciences, is the first author of this work. This research was supported by the Ministry of Science and Technology, the National Foundation of China, the Chinese Academy of Sciences, and Anhui Province.
Link:
https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.128.120402
