The reporter learned from China University of Science and Technology that the school's Guo Guangcan academic team Li Chuanfeng, Zhou Zongquan and others successfully developed a multi-degree-of-freedom parallel-multiplexed solid-state quantum memory, which realized the first time in the world to realize three-degree-of-freedom multiplexing quantum storage and demonstrated time. And any photon pulse operation function with frequency freedom. This achievement was recently published in the international journal Nature Communication.
Due to the insurmountable fiber channel loss, the ground-based quantum communication distance is limited to the order of 100 kilometers. The quantum memory-based quantum relay scheme can effectively overcome the channel loss and expand the working distance of quantum communication, so the quantum memory is the future long-range quantum. The core device of communication and quantum network. For quantum memory, because of its quantum coherence, a memory cell can store a large number of qubits at a time. This is the concept of multiplexing. In principle, the degrees of freedom of quantum memory can be Reuse.
In order to further enhance the multiplexing capacity of quantum memory, the research group innovatively adopts a multi-degree-of-freedom parallel multiplexing storage scheme. For example, there are M storage modes in the first degree of freedom, and N modes in the second degree of freedom. The three degrees of freedom have P modes, and the total number of multiplexing modes of the quantum memory is the product of the number of degrees of each degree of freedom, that is, M × N × P. The research group selects the time of the photons, and the spatial and frequency degrees of freedom are used for parallel multiplexing. In the world, the three degrees of freedom of the multiplexed quantum storage are realized first. In the experiment, two time modes, two frequency modes, three spatial modes, and the total number of modes are 2×2×3=12. The experimental results demonstrate the feasibility of multi-degree-of-freedom parallel multiplexing quantum storage.
The research team further proved that their memory can perform arbitrary pulse operations in time and frequency degrees of freedom. Representative operations include pulse sequencing, splitting, frequency division, inter-frequency photon combining and narrow-band filtering. Experimental results show that at all During these operations, the three-dimensional quantum states carried by photons maintain a fidelity of about 89%. This result is expected to find more applications in the field of linear optical quantum computing.
