This work from researchers led by Xiao-Hui Bao is an important step toward building a large-scale quantum network. They have previously shown famous photon storage with this technique using Rydberg superatoms. This proof-of-principle has been published in the journal Physical Review Letters. It brings a new deterministic method for tangling the quantum state of two nodes, a key-building block for future large-scale quantum networks.
The research showed that making heralded storage with two Rydberg superatoms was harder than we had thought at first. Even with those intricacies, Bao and his team have developed a less complicated technique to achieve heralded storage. Indeed, this ability has only been long thought to be the province of cavity quantum electrodynamics (QED) systems.
Understanding Heralded Storage
Heralded storage is critical to realizing large-scale quantum networks. These networks are meant to link together many such quantum devices. Researchers have been testing different methods to make these networks a reality for the past few decades.
Prior to this work, celebrated storage was mostly tied to cavity-QED systems. That is what Bao wanted to highlight in their findings—Rydberg superatoms can be really, really good at doing that job too. “Heralded storage has traditionally been considered a capability unique to cavity-QED systems,” he stated.
The researchers used two Rydberg superatoms to prove this heralded storage method. This approach makes it a lot easier. It further eliminates the requirement of an intermediate node to establish entanglement between the two respective nodes.
“As an application, our current experiment demonstrates the generation of two-node entanglement via heralded storage, eliminating the need for an intermediate node,” – Xiao-Hui Bao.
Challenges and Innovations
The team struggled with unforeseen challenges when making their first proposal to successfully demonstrate heralded storage. Bao explained, “In our initial proposal for demonstrating heralded storage, we planned to use two Rydberg superatom setups, with the input photonic qubit encoded in the spatial degree of freedom.”
“While this scheme appeared straightforward, its implementation demanded extensive experimental resources and introduced considerable complexity,” Bao noted.
Even with these obstacles, the researchers have produced remarkable results. They have pioneered new approaches, such as photon compensation in Rydberg superatoms. These techniques were first employed to generate both atom-photon entanglement and multiphoton entanglement.
“Prior to this work, we introduced a technique we called photon compensation in a Rydberg superatom, which we used to demonstrate the generation of atom-photon entanglement, and multiphoton entanglement,” – Xiao-Hui Bao.
Implications for Quantum Networks
The onus of this research has big implications for the progress of quantum networks. Through their work, Bao and his colleagues are helping to lay the groundwork for improved quantum communication systems. They have implemented a feasible protocol for obtaining entanglement between distant superatoms through heralded storage of photons.
Our research team is already hard at work scanning for promising new techniques and experimental platforms. These abstractions would enable new capabilities that lead the development of wide-area, large-scale quantum networks. Their recent findings are just a step in the right direction to making that possible.
“However, our scheme and experimental results demonstrate that a Rydberg superatom can perform this task effectively as well,” – Xiao-Hui Bao.
The full research is available for a deeper dive, under DOI 10.48550/arxiv.2504.05021.