Schematic experimental setup. The qudit signal encoded in POV mode via SLM 1 and lens L1 is mapped into the atomic array for later storage. Here the signal and control fields are both circularly polarized (σ+), and the control field is expanded to be 4mm in size to completely cover the signal field in the center of the bracket. Credit: Dong et al., Physical Examination Letters (2023). DOI: 10.1103/PhysRevLett.131.240801
Many physicists and engineers have attempted to develop highly efficient quantum technologies capable of performing functions similar to those of conventional electronics by exploiting the effects of quantum mechanics. This includes high-dimensional quantum memories, storage devices with greater information capacity and greater noise resilience than two-dimensional quantum memories.
Until now, the development of these large memories has proven difficult and most attempts have not resulted in satisfactory efficiency. In an article published in Physical Examination LettersA research team from the University of Science and Technology of China and Hefei Normal University recently introduced an approach to realize highly efficient 25-dimensional memory based on cold atoms.
“Our group uses the orbital angular momentum mode in the space channel to study high-dimensional quantum storage and has accumulated a wealth of research experience and technology,” said Dong Sheng Ding, co-author of the paper. article, at Phys.org. “Achieving large-scale, high-efficiency quantum storage has always been our goal.”
In their previous studies, Ding and his colleagues found that the singular properties of a spatial pattern known as a perfect vortex optical field could be particularly advantageous for the development of high-dimensional quantum memories. This prompted them to exploit the mode-independent interaction between light and matter associated with this model to achieve efficient, high-dimensional quantum storage.
“The basic principle of our storage device relies on the transparency phenomenon induced by electromagnetism, which is the interaction between light and matter,” Ding explained. “In simple terms, the signal photons are slowed down to zero speed in the medium and stored for a certain time. Then the information stored on the signal photons can be retrieved by the control light.”
The quantum system created by the researchers is composed of signal photons, a control light beam, a cold Rubidium atomic assembly that serves as a storage medium, and a spatial light modulator that encodes and decodes the information high-dimensional quantum. The team’s memory encodes high-dimensional information on the photons of the signal, ultimately realizing the storage of high-dimensional information in the medium.
“Before our work, efficient quantum memory was limited to two-dimensional quantum storage systems,” Ding said. “The advantage of our work lies in expanding the storage dimension from two to 25, enabling the preparation of high-dimensional memory that operates in high-dimensional Hilbert space. Not only does this significantly increase the memory capacity and increases the transmission capacity of quantum communication, but also has potential implications for fault-tolerant quantum computing.
In initial tests, the researchers demonstrated that their quantum memory can store high-dimensional states in 25 dimensions. However, their system can also store arbitrary high-dimensional states ranging from 1 to 25 dimensions (i.e., including 3-dimensional, 5-dimensional, 10-dimensional states, etc.).
“Our results demonstrate the compatibility of our memory with high-dimensional programmable quantum states in the range of 1 to 25 dimensions,” Ding said. “In addition, we theoretically analyzed the scalability of the dimensionality of our memory. By further optimizing the optical path design, we can achieve efficient storage of up to 100 higher-dimensional states or even more, demonstrating the unique advantages of our large storage system. “.
Recent work by Ding and colleagues has introduced a very promising new method for achieving efficient high-dimensional quantum storage. In the future, this approach could be used to create various high-dimensional quantum memories, which could in turn contribute to the realization of other quantum technologies, such as high-dimensional quantum repeaters.
“Our approach notably makes it possible to realize a practical high-dimensional quantum memory,” added Ding. “In the future, we will establish high-dimensional quantum repeaters using high-dimensional quantum memories, enabling high-dimensional quantum communication between two or more distant quantum nodes.”
More information:
Ming-Xin Dong et al, Highly efficient storage of 25-dimensional photonic Qudit in a quantum memory based on cold atoms, Physical Examination Letters (2023). DOI: 10.1103/PhysRevLett.131.240801
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