Creation of memory-memory entanglement in a metropolitan quantum network. (https://pubmed.ncbi.nlm.nih.gov/38750235/)

These scientists wanted to create a big quantum network that could work over a whole city. They had already done smaller experiments in labs with just two nodes, but now they wanted to try it with more nodes. They used three memory nodes, each with something called an atomic ensemble quantum memory. These memory nodes were placed far apart from each other, about 12.5 kilometers. They also had special devices to help detect when entanglement, a special connection in quantum physics, was successful.

The scientists made sure that the signals sent between the memory nodes were stable and controlled. They were able to create entanglement between any two memory nodes at the same time. This means that the memory nodes were connected in a special way that allowed them to share information instantly. The memory in these nodes could hold information for a long time, even longer than it took for a signal to travel back and forth between them.

This study helps us understand how quantum networks can work over large areas like cities. It's like laying the groundwork for a special kind of internet that uses quantum physics.

Liu JL., Luo XY., Yu Y., Wang CY., Wang B., Hu Y., Li J., Zheng MY., Yao B., Yan Z., Teng D., Jiang JW., Liu XB., Xie XP., Zhang J., Mao QH., Jiang X., Zhang Q., Bao XH., Pan JW. Creation of memory-memory entanglement in a metropolitan quantum network. Nature. 2024 May;629(8012):579-585. doi: 10.1038/s41586-024-07308-0. Epub 2024 May 15.