Topological Skyrmions Enable Robust Information Storage for Microsecond-Scale Applications

Topological structures of light, known as skyrmions, hold considerable promise for future information storage technologies because their defining property, the skyrmion number, resists disruption. Jinwen Wang, Xin Yang, and Yun Chen, alongside colleagues at their respective institutions, now demonstrate the successful storage and retrieval of these skyrmions within a cold rubidium vapour. The team utilises a novel dual-path electromagnetically induced transparency memory to achieve this, and importantly, proves the skyrmion number remains stable for several microseconds, even when subjected to significant disturbances. This achievement represents a crucial step forward in developing topologically protected photonic technologies, offering a pathway to more robust and reliable data storage systems.

The team utilises a novel dual-path electromagnetically induced transparency memory, proving the skyrmion number remains stable for several microseconds, even when subjected to significant disturbances. This achievement represents a crucial step forward in developing topologically protected photonic technologies, offering a pathway to more robust and reliable data storage systems.

Dual-Path Storage of Optical Skyrmions in Vapor

Scientists pioneered a method for storing and retrieving optical skyrmions, topological structures of light, within a cold 87Rb vapor using a dual-path electromagnetically induced transparency (EIT) memory. The study employed a configuration where the two spatial modes of an optical skyrmion are spatially separated and independently stored within the atomic ensemble. Researchers drove transitions between atomic energy levels using both probe and control beams to establish the EIT protocol, enabling coherent storage of the light’s polarization state. To implement the dual-path memory, scientists carefully separated the spatial modes of the input skyrmion, directing each mode into a distinct path within the cold atomic vapor. This configuration allowed for independent storage of each spatial mode, effectively creating a spatially separated memory for the complete skyrmion structure.

The team meticulously controlled beam parameters to optimize the EIT effect and maximize storage efficiency. The experimental setup addressed challenges related to imbalances in storage efficiency and phase differences between the two paths. Differences in the intensity distribution of the spatial mode profiles led to unequal storage efficiency, and dispersion accumulated along each path introduced phase differences. Scientists compensated for these effects by carefully calibrating beam intensities and optimizing the atomic vapor density. Despite experiencing decoherence-induced loss of storage efficiency, the study demonstrated that the skyrmion number, a fundamental topological invariant, remained conserved for storage times exceeding several microseconds. This marks the first demonstration of topologically protected storage of light, paving the way for robust quantum memories and photonic technologies.

Optical Skyrmion Storage Preserves Topology

Scientists have demonstrated the storage and retrieval of optical skyrmions, complex structures of light, within a cold rubidium vapour, marking a significant step towards topologically protected photonic technologies. This work represents the first experimental demonstration of maintaining the skyrmion number, the defining property of these skyrmions, during coherent storage for up to several microseconds. The team achieved this using a dual-path electromagnetically induced transparency memory, a technique that leverages the unique quantum properties of atoms to hold information.

Crucially, experiments revealed that the skyrmion number remains invariant even when subjected to imbalanced loss between the two storage paths and substantial perturbations in the power of the control beams. This resilience is due to the topological nature of skyrmions, making them robust against disturbances that would typically degrade conventional optical signals. The researchers generated optical skyrmions using a spatial light modulator and interferometer, then stored them within a cigar-shaped cloud of cold rubidium atoms prepared in a magneto-optical trap. By converting the skyrmion into a superposition of separate paths, encoded in the polarization of the light, they were able to utilize the dual-path storage protocol.

Measurements confirm that even with asymmetric storage efficiency between the two paths, acting as a source of noise, the topological invariant remains intact. The storage efficiency is affected by the order of the Laguerre-Gaussian modes used to create the skyrmions, with higher order modes experiencing reduced optical depth and weaker light-atom interaction. Despite these challenges, the skyrmion number remained stable throughout the storage period. This contrasts sharply with conventional polarization-based storage, where imbalances or errors severely degrade signal reconstruction. The breakthrough delivers a pathway towards robust information carriers compatible with imperfect photonic memory platforms, offering potential for future storage devices based on skyrmionic structures.

Topological Protection Confirmed in Light Skyrmions

This research demonstrates the first successful storage and retrieval of optical skyrmions, topological structures of light, within a cold atomic vapour using a dual-path electromagnetically induced transparency memory. Crucially, the team established that the skyrmion number, the defining property of these skyrmions, remains unchanged during storage lasting several microseconds, even when subjected to imbalances in signal loss and variations in control beam power. This preservation of the skyrmion number confirms the inherent topological protection within these structures, preventing the stored information from degrading.

The findings validate that topological protection is not compromised by the complex interactions between light and matter, or by decoherence processes common in quantum memories. This work moves beyond a simple proof-of-principle demonstration, establishing a topologically protected subspace for encoding quantum information, potentially through superpositions of different skyrmion states. The demonstrated resilience to realistic noise within the storage system represents a foundational step towards leveraging topological invariance as a resource for protecting quantum information in future photonic technologies. The authors acknowledge that their primary focus was establishing the preservation of the topological invariant, and future work could optimise memory performance or investigate stability under varying control parameters. Further investigation into potential disruption mechanisms at high power levels could also reveal the limits of this topological optical memory.