Exact quantum critical states with a superconducting quantum processor

• URL: http://arxiv.org/abs/2502.19185v2
• Date: Tue, 25 Mar 2025 14:12:39 GMT
• Title: Exact quantum critical states with a superconducting quantum processor
• Authors: Wenhui Huang, Xin-Chi Zhou, Libo Zhang, Jiawei Zhang, Yuxuan Zhou, Bing-Chen Yao, Zechen Guo, Peisheng Huang, Qixian Li, Yongqi Liang, Yiting Liu, Jiawei Qiu, Daxiong Sun, Xuandong Sun, Zilin Wang, Changrong Xie, Yuzhe Xiong, Xiaohan Yang, Jiajian Zhang, Zihao Zhang, Ji Chu, Weijie Guo, Ji Jiang, Xiayu Linpeng, Wenhui Ren, Yuefeng Yuan, Jingjing Niu, Ziyu Tao, Song Liu, Youpeng Zhong, Xiong-Jun Liu, Dapeng Yu,
• Abstract summary: Anderson localization physics features three fundamental types of eigenstates: extended, localized, and critical.<n>We report the unambiguous experimental realization of critical states governed by a rigorous mechanism for exact quantum critical states.<n>We resolve the energy-dependent transition between localized and critical states, revealing the presence of anomalous mobility edges.
• Score: 17.380822949477384
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Anderson localization physics features three fundamental types of eigenstates: extended, localized, and critical. Confirming the presence of critical states necessitates either advancing the analysis to the thermodynamic limit or identifying a universal mechanism which can rigorously determine these states. Here we report the unambiguous experimental realization of critical states, governed by a rigorous mechanism for exact quantum critical states, and further observe a generalized mechanism that quasiperiodic zeros in hopping couplings protect the critical states. Leveraging a superconducting quantum processor with up to 56 qubits, we implement a programmable mosaic model with tunable couplings and on-site potentials. By measuring time-evolved observables, we identify both delocalized dynamics and incommensurately distributed zeros in the couplings, which are the defining features of the critical states. We map the localized-to-critical phase transition and demonstrate that critical states persist until quasiperiodic zeros are removed by strong long-range couplings, highlighting a novel generalized mechanism discovered in this experiment and shown with rigorous theory. Finally, we resolve the energy-dependent transition between localized and critical states, revealing the presence of anomalous mobility edges.

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