Supported by projects from the National Natural Science Foundation of China (Grant Nos. T2225008, 92365301, 12274368, 12274367, 12174342, 12322414, 12404570, 12404574, U20A2076, 12075128, 123B2072), a research team led by Dong-Ling Deng from Tsinghua University, in collaboration with Haohua Wang’s group at Zhejiang University and Qiujang Guo’s group from ZJU-Hangzhou Global Scientific and Technological Innovation Center and other international collaborators, has observed a distinct type of robust topological edge modes at finite temperatures in a disorder-free quantum system with a 100-qubit superconducting quantum processor for the first time. The related findings, entitled "Topological prethermal strong zero modes on superconducting processors," were published in Nature on August 27, 2025. Link to the paper: https://www.nature.com/articles/s41586-025-09476-z.

Figure: The “Tianmu-2” Superconducting chip and the main experimental results of the finite-temperature topological edge states

Symmetry-protected topological edge states (modes) arise from novel phases of matter in condensed matter physics. Due to their inherent robustness against certain types of perturbations, these edge states have significant potential for applications in quantum information science. However, such edge states typically only survive the ground state of a system at zero temperature. At finite-temperatures, they are highly susceptible to thermal excitations, which can lead to the loss of stored quantum information. Thus, protecting quantum states from thermal fluctuations remains a key challenge in condensed matter physics and quantum information research.

To address this issue, the joint research team proposed a novel approach utilizing prethermalization mechanisms to protect topological edge states. Unlike conventional methods that rely on many-body localization to confine thermal excitations, this strategy does not require introducing disordered random potentials. Instead, it leverages emergent symmetries during the system’s evolution to provide additional protection for the edge states, effectively suppressing their interaction with thermal excitations.

To validate this approach, the team employed the 125-qubit “Tianmu-2” superconducting quantum processor from Zhejiang University to realize a one-dimensional symmetry-protected topological chain consisting of 100 qubits. With the support of high programming flexibility and high-fidelity quantum gates, the researchers observed thermal-excitation-robust topological edge states throughout an evolution involving approximately 270 layers of two-qubit quantum gates. Furthermore, the team conducted in-depth investigations into the dynamics of thermal excitations and the mechanism of emergent symmetries in the prethermal regime. Based on these insights, the joint team performed quantum encoding on two topological edge states, successfully preparing a set of logical Bell states that exhibit strong resilience against thermal excitations.

This study demonstrates the feasibility of realizing long-lived, disturbance-resistant qubits in finite-temperature disorder-free systems, offering a new pathway for building noise-resilient quantum memory and quantum control technologies in the future.