The team of Guo Guangcan of the University of Science and Technology of China has made important experimental progress in quantum simulation
The team of Academician Guo Guangcan from the University of Science and Technology of China has made important experimental progress in quantum simulation based on artificial synthetic dimensions. The team Li Chuanfeng, Xu Jinshi, Han Yongjian and others bound photons carrying different orbital angular momentum (also known as vortex photons) in a degenerate optical resonator, and artificially synthesized one-dimensional topological crystals by introducing the spin-orbit coupling of photons. Lattice, pioneering a new approach for topological quantum simulations. The research results were published in the internationally renowned academic journal Nature Communications on April 19.
Dimension is an important physical quantity that determines the properties of matter in the universe. However, in scientific research, due to the limitation of the three-dimensional physical world, it is often difficult to study the properties and evolution characteristics of physical systems with more than three dimensions. In response to this problem, researchers propose that it can be solved by artificially synthesizing dimensions. For example, by introducing two synthetic dimensions into a three-dimensional system, the physical properties of five dimensions can be studied on that system.
Schematic diagram of experimental setup and theoretical model: a. Degenerate optical resonator b. Synthetic photon orbital angular momentum lattice
The number of orbital angular momentum carried by vortex photons can be infinite in principle, which is an ideal carrier for constructing artificial synthetic dimensions. As early as 2015, the research group of Professor Zhou Zhengwei of the Key Laboratory of Quantum Information of the Chinese Academy of Sciences first theoretically proposed a scheme to realize quantum simulation based on the angular momentum dimension of artificially synthesized photons. Li Chuanfeng, Xu Jinshi and others have conducted long-term experimental exploration in this direction, and successively built degenerate optical cavities based on plane mirrors, spherical mirrors and ellipsoid mirrors, and realized the resonance of more than 46-order orbital angular momentum modes in the cavity.
On this basis, the research group creatively introduced a liquid crystal phase plate with anisotropy into the standing wave degenerate cavity (as shown in Fig. a) to realize the intracavity vortex photon orbital angular momentum and photon spin (ie polarization) coupling. The orbital angular momentum carried by the photons in the cavity is integer discrete, corresponding to a one-dimensional discrete lattice. Therefore, photons carrying different orbital angular momentums can be equivalent to quasiparticles located on different lattice points, and the photons with different orbital angular momentums can be coupled through the spin degrees of freedom, thereby simulating the particle movement between different lattice points. Jump back and forth (as shown in Figure b). Using resonance spectroscopy detection technology, the research group directly characterized the density of states and energy band structure of the spin-orbit coupled system. Taking advantage of the excellent tunability of the experimental setup, the research group clearly demonstrated the evolution of the energy band opening and closing of the periodically driven system. The research group further introduced different evolution time series, systematically studied the characteristics of different topological structures and detected the topological winding number.
This achievement verifies the feasibility of utilizing the intrinsic spin and orbital angular momentum of vortex photons as artificial synthetic dimensions, providing a highly compact experimental platform for studying rich topological physics systems.
The co-first authors of the paper are Yang Mu, a doctoral student at the Key Laboratory of Quantum Information, Chinese Academy of Sciences, and Zhang Haoqing and Liao Yuwei, a master's student. This research was supported by the Ministry of Science and Technology, the National Foundation of China, the Chinese Academy of Sciences, and Anhui Province.
