Recently, in collaboration with professor Wang Huitian from Nanjing University, the research team led by professor Li Yongnan, the School of Physics, Nankai University, proposed the method of using two-dimensional detector to realize scan-free quantum tomography. The research findings were published on Physical Review Letters under the title of “Two-Measurement Tomography of High-Dimensional Orbital Angular Momentum Entanglement”. 

The core idea is to use two-dimensional array detector instead of the traditional single-pixel detector to obtain high-dimensional quantum information from the two-dimensional coincidence counting based on the principle of interference and Discrete Fourier Transform. This method is scan-free and independent of dimension, which only requires two measurements to reconstruct the density matrix with very high fidelity for two-photon HD OAM entanglement with any dimension. The idea can be applied to other spatial mode entanglement, multi-photon entanglement and mixed state entanglement, laying a solid foundation for high-capacity quantum communication and quantum process tomography. In the future, it would provide more interesting and efficient measuring method for complex conditions with the combination of machine learning, such as the application of HD photon quantum information in the atmosphere and optical fiber. 

Figure: Diagram of Efficient Characterization Method of Quantum OAM Entanglement

The paper's co-first authors are Li Yi and Huang Shuangyin, who respectively received bachelor's degree and doctoral degree from Nankai University, while the co-correspondent authors are professor Li Yongnan from Nankai University and professor Wang Huitian from Nanjing University. 

(Edited and translated by Nankai News Team)