The Chinese University of Science and Technology, etc., realized the transformation of quantum states under incoherent operation

[ Instrument Network Instrument R & D ] Guo Guangcan, an academician of the Chinese Academy of Sciences and a professor at the University of Science and Technology of China, has made new progress in quantum coherence theory and experimental research. The cooperation of physicists, for the first time, theoretically completely solved the problem of transforming qubits in non-coherent operations (operations that do not increase coherence) and designed experiments to verify the results. The results were published in the international academic journal of physics on February 13th. Quantum Information.

Quantum coherence, as a kind of quantification of quantum superposition, is the core of quantum physics and quantum information, and has important applications in various quantum tasks (such as quantum computing, quantum communication, etc.). The recent strict definition of quantum coherence has promoted the development of quantum coherence resource theory. The resource theory of quantum coherence mainly studies the operational value of quantum superposition. One of the core issues is the transformation of quantum states under non-coherent operation. Xiang Guoyong's research group and its theoretical collaborators have completely solved the problem of transforming qubits under non-coherent operation in theory, and extended the results to the study of coherent transformation in a distributed system, completely solving the two-body pure Assisted transformation of states and partially assisted transformation of mixed states.

Based on these theoretical work, Xiang Guoyong's research group designed a series of experiments to verify. They coded the qubits into the polarization state of the photon, and for the first time designed an all-optical device for strictly non-coherent operation. . The experimental results show that the use of optical technology can facilitate the research of quantum state transformation under incoherent operation, which paves the way for the use of existing optical technology to achieve coherent transformation in specific applications.

In recent years, Xiang Guoyong's research group has made a series of progress in the theoretical and experimental research of coherence, following the first implementation of auxiliary extraction of quantum coherence in 2017 (Wu et al. Optica 4, 454–459 (2017)) and After proposing and verifying the cyclic transformation of quantum coherence and quantum correlation in 2018 (Wu et al. Phys. Rev. Lett. 121, 050401 (2018)), this achievement completely solved the transformation of qubits in the theory of coherent resources for the first time. Question and was highly appreciated by the reviewers.

The co-first authors of the article are Wu Kangda, Ph.D. student of the Key Laboratory of Quantum Information of the Chinese Academy of Sciences, and Thomas Theurer of the University of Ulm, Germany. Corresponding authors are Xiang Guoyong, professor of the laboratory, and Alexander Streltsov, PhD, Warsaw University.

The research was supported by the Ministry of Science and Technology, the National Funding Committee, the Chinese Academy of Sciences, and Anhui Province.