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Paper 1

Low-depth quantum state preparation

Xiao-Ming Zhang, Man-Hong Yung, Xiao Yuan

Year
2021
Journal
Physical Review Research
DOI
10.1103/physrevresearch.3.043200
arXiv
-

No abstract.

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Paper 2

Criticality on Rényi defects at (2+1)$d$ O(3) quantum critical points

Yanzhang Zhu, Zhe Wang, Meng Cheng, Zheng Yan

Year
2026
Journal
arXiv preprint
DOI
arXiv:2605.00104
arXiv
2605.00104

At a quantum critical point, the universal scaling behavior of Rényi entanglement entropy is controlled by the universality class of the codimension-two Rényi (or conical) defects in the infrared theory. In this work we perform a systematic study of critical correlations along Rényi defect lines in (2+1)d quantum spin models realizing quantum phase transitions described by the O(3) Wilson-Fisher universality class, using large-scale quantum Monte Carlo simulations. We present numerical evidence that, for a fixed Rényi index $n$, there exist multiple Rényi defect universality classes, with distinct critical exponents for the O(3) order parameter on the defect. These universality classes are realized by choosing microscopically different entanglement cuts in lattice models, which we classify as ordinary, special and extraordinary according to their relation to surface criticality. For the extraordinary entanglement cut, we further find evidence for a phase transition on the defect as a function of the Rényi index. Our results highlight the key role of defect universality classes in determining the universal scaling of Rényi entropy, and provide a framework for understanding the previously observed dependence of Rényi entropy scaling on microscopic lattice details.

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