From The University of Science and Technology of China [中国科学技术大学](CN) of the Chinese Academy of Sciences [中国科学院](CN): “Optimized Method to Detect High-dimensional Entanglement” 

From The University of Science and Technology of China [中国科学技术大学](CN) of the Chinese Academy of Sciences [中国科学院](CN)

Dec 03, 2021

Jane FAN Qiong
University of Science and Technology of China
englishnews@ustc.edu.cn

Editor: LIU Jia

In a study published in Physical Review Letters, the team led by Academician GUO Guangcan from the University of Science and Technology of China of the Chinese Academy of Sciences (CAS), collaborating with Prof. WANG Zizhu from The University of Electronic Science and Technology of China [电子科技大学] (CN), proposed an optimized detection method for high-dimensional entanglement for the first time.

How to prepare and detect quantum entanglement is the key to quantum information processing. With the increase of dimensions and particles, the higher-dimensional system brings about both the sheer detection difficulty in computation and the excess costs in resources. Apparently, the traditional detection methods barely work.

Confronted with the challenges in high-dimensional entanglement detection, researchers adopted fidelity-based entanglement witnesses to detect a 32-dimensional entanglement state with its fidelity reaching the highest level in the world. However, for common non-maximally high-dimensional entanglement detection, conventional fidelity-based witnesses were not applicable.

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Experimental results of the optimal 1−pI−pII for states. Experimental values for p=0 , 0.2, 0.4, 0.6, 0.8, and 1 of state ρpUNF in (a) and p=0.5 , 0.6, 0.7, 0.8, 0.9, and 1 of state ρpISO in (b) are shown in blue. The solid red lines represent optimal values computed by the SDP solver. States in the green regions are three unfaithful in (a) and two unfaithful in (b). The entanglement dimension is certified when 1−pI−pII>0. Credit: DOI: 10.1103/PhysRevLett.127.220501 and phys.org.

To remove this barrier, researchers need to supplement fidelity-based witnesses with experiment-friendly protocols that can detect unfaithful entanglement. Following this path, they designed a method to automatically search for optimal protocols for certifying high-dimensional bipartite entanglement.

They first experimentally prepared a series of high-dimensional bipartite target states in an innovative way. And then they implemented a few local measurements to achieve the optimal quantum entanglement detection. To certify the entanglement in four-dimensional photonic states, only some three-setting protocols were adopted.

This study solves the problem of detecting high-dimensional bipartite entangled states. It lays a foundation for realizing multiple high-dimensional quantum information processing and promotes the research of quantum physics in high-dimensional systems.

See the full article here.

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The The University of Science and Technology of China [中国科学技术大学](CN) of the Chinese Academy of Sciences [中国科学院](CN) is a national research university in Hefei, Anhui, China, under the direct leadership of the Chinese Academy of Sciences [中国科学院](CN). It is a member of the C9 League, China’s equivalent of the Ivy League. It is also a Chinese Ministry of Education Class A Double First Class University. Founded in Beijing by the CAS in September 1958, it was moved to Hefei in the beginning of 1970 during the Cultural Revolution.

USTC was founded with the mission of addressing urgent needs to improve China’s economy, defense infrastructure, and science and technology education. Its core strength is scientific and technological research, and more recently has expanded into humanities and management with a strong scientific and engineering emphasis. USTC has 12 schools, 30 departments, the Special Class for the Gifted Young, the Experimental Class for Teaching Reform, Graduate Schools (Hefei, Shanghai, Suzhou), a Software School, a School of Network Education, and a School of Continuing Education. In 2012 the Institute of Advanced Technology, University of Science and Technology of China was founded.

USTC was founded in Beijing by The Chinese Academy of Sciences [中国科学院] (CN) in September 1958. The Director of CAS, Mr. Guo Moruo was appointed the first president of USTC. USTC’s founding mission was to develop a high-level science and technology workforce, as deemed critical for development of China’s economy, defense, and science and technology education. The establishment was hailed as “A Major Event in the History of Chinese Education and Science.” CAS has supported USTC by combining most of its institutes with the departments of the university. USTC is listed in the top 16 national key universities, becoming the youngest national key university.

In 1969, during the Cultural Revolution, USTC was moved to Anhui province and eventually settled in Hefei in 1970.

USTC set up the Special Class for the Gifted Young and the first graduate school in China in 1978. The campus for graduate study in Hefei was established in 1986. Original campus for graduate study in Beijing was later renamed the Graduate School of the CAS in 2001 and University of Chinese Academy of Sciences in 2012.

In 1995, USTC was amongst the first batch of universities obtaining support through the National 9th Five-Year Plan and the “Project 211”. In 1999, USTC was singled out as one of the 9 universities enjoying priority support from the nation’s “Plan of Vitalizing Education Action Geared to the 21st Century”. Since September 2002, USTC has been implementing its “Project 211” construction during the 10th National Development Plan.