Coupling Schematic of Three Graphene Resonator Tandem Structures and Scanning Electron Microscope Image.
Chinese Academy of Sciences, Professor Guo Guangcan led by the CAS Key Laboratory of Quantum Information, made new progress in the nano-mechanical and electrical systems (NEMS) .The laboratory professor Guo Guoping, associate researcher Deng Guangwei and the United States University of California Merced Professor Tian Lin cooperation, in the study of two graphene nanocrystal resonator mode coupling process, the innovative introduction of a third resonator as a phonon cavity mode, the successful realization of non-neighbors mode coupling, cavity mode by simply adjusting the frequency can be Achieve non-neighbors coupling strength from weak coupling to strong coupling of continuous changes. January 26, the relevant research results published in Nature Communications.
Nano resonators have the advantages of small size, good stability and high quality factor, which are excellent carriers for information storage and manipulation. In order to achieve the information transfer between different resonant modes, the controllable coupling between modes needs to be realized first. In recent years, Different research groups focused on different modes of resonance in the same resonator and the mode coupling mechanism between adjacent resonators.After Guo GuoPing's research group had realized the strong coupling between the adjacent resonators and the resonance modes A series of work published in the "Nano Letters." However, how to achieve non-neighbors, tunable resonant mode coupling, there has been no good international solution, there is no relevant experimental reports.
In response to this challenge, the research team designed and prepared three graphene nanocantioresters in series. As shown in the following figure, the resonant frequency of each resonator can be extensively adjusted by the metal electrodes at the bottom of each. Therefore, The appropriate electrode voltage can achieve the resonant coupling of the three resonators.The research group first measured the mode splitting between the two adjacent resonators and proved that the adjacent resonator can reach the strong coupling region in the series structure, After exploring the first and third resonator coupling between the conditions created.Through experimental exploration, the research team found that when the resonant frequency of the intermediate resonator transferred far above (or much lower than) the resonance of the two resonators Frequency, the mode splitting between the two resonators can not occur, that is, the coupling strength between them is very small. However, when the resonant frequency of the intermediate resonator gradually approaches the resonant frequency of the two resonators, the mode split Crack, and split value increases gradually.
This process is similar to the Raman process in the optical field where an intermediate resonator is equivalent to a phononic cavity mode and the two resonators create an equivalent coupling by exchanging the phonons with the cavity mode (see below) According to the theory of optical Raman process, the equivalent coupling strength due to the virtual photon exchange decreases with the increase of detuning, which is expected to be similar to that of the research group found in the phonon coupling experiment. Therefore, The research group deduces the Raman coupling theory of the phonon coupling system with reference to the optical Raman process and finds that the experimental data are in good agreement with the theory.
This experiment is the first one to realize the resonant mode non-neighbors coupling in the nanometer resonator system, which is of great impetus to the development of the nanometer electromechanical resonator field and creates the conditions for the future long-range information phonon mode transmission in the quantum range Research has been funded by the Ministry of Science and Technology, the National Natural Science Foundation of China, the Chinese Academy of Sciences and the Ministry of Education.
