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Main Authors: Numajiri, Tatsuya, Yamashika, Shion, Tanizawa, Tomonori, Yoshii, Ryosuke, Takeuchi, Yuki, Tsuchiya, Shunji
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2510.00548
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author Numajiri, Tatsuya
Yamashika, Shion
Tanizawa, Tomonori
Yoshii, Ryosuke
Takeuchi, Yuki
Tsuchiya, Shunji
author_facet Numajiri, Tatsuya
Yamashika, Shion
Tanizawa, Tomonori
Yoshii, Ryosuke
Takeuchi, Yuki
Tsuchiya, Shunji
contents Graph states are entangled states that are essential for quantum information processing. As experimental advances enable the realization of large-scale graph states, efficient fidelity estimation methods are crucial for assessing their robustness against noise. However, calculations of exact fidelity become intractable for large systems due to the exponential growth in the number of stabilizers. In this work, we show that the fidelity between any ideal graph state and its noisy counterpart under IID Pauli noise can be mapped to the partition function of a classical spin system, enabling efficient computation via statistical mechanical techniques. Using this approach, we analyze the fidelity for regular graph states under depolarizing noise and uncover the emergence of phase transitions in fidelity between the pure-state regime and the noise-dominated regime. Specifically, in 2D, phase transitions occur only when the degree satisfies $d\ge 6$, while in 3D they already appear at $d\ge 5$. However, for graph states with excessively high degree, such as fully connected graphs, the phase transition disappears. Robustness of graph states against noise is thus determined by their connectivity and spatial dimensionality. Graph states with lower degree and/or dimensionality, which exhibit a smooth crossover, demonstrate greater robustness, while highly connected or higher-dimensional graph states are more fragile. Extreme connectivity, as the fully connected graph state possesses, restores robustness. Furthermore, we show that the fidelity can be rewritten in the form of the partition function of a constraint-percolation problem. Within this picture, we discuss the qualitative difference between 2D regular graph states with $d=6$ and $d=5$ regarding the presence or absence of a phase transition, as well as the suppressed critical behavior of fully connected graph states.
format Preprint
id arxiv_https___arxiv_org_abs_2510_00548
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Phase Transitions and Noise Robustness of Quantum Graph States
Numajiri, Tatsuya
Yamashika, Shion
Tanizawa, Tomonori
Yoshii, Ryosuke
Takeuchi, Yuki
Tsuchiya, Shunji
Quantum Physics
Statistical Mechanics
Graph states are entangled states that are essential for quantum information processing. As experimental advances enable the realization of large-scale graph states, efficient fidelity estimation methods are crucial for assessing their robustness against noise. However, calculations of exact fidelity become intractable for large systems due to the exponential growth in the number of stabilizers. In this work, we show that the fidelity between any ideal graph state and its noisy counterpart under IID Pauli noise can be mapped to the partition function of a classical spin system, enabling efficient computation via statistical mechanical techniques. Using this approach, we analyze the fidelity for regular graph states under depolarizing noise and uncover the emergence of phase transitions in fidelity between the pure-state regime and the noise-dominated regime. Specifically, in 2D, phase transitions occur only when the degree satisfies $d\ge 6$, while in 3D they already appear at $d\ge 5$. However, for graph states with excessively high degree, such as fully connected graphs, the phase transition disappears. Robustness of graph states against noise is thus determined by their connectivity and spatial dimensionality. Graph states with lower degree and/or dimensionality, which exhibit a smooth crossover, demonstrate greater robustness, while highly connected or higher-dimensional graph states are more fragile. Extreme connectivity, as the fully connected graph state possesses, restores robustness. Furthermore, we show that the fidelity can be rewritten in the form of the partition function of a constraint-percolation problem. Within this picture, we discuss the qualitative difference between 2D regular graph states with $d=6$ and $d=5$ regarding the presence or absence of a phase transition, as well as the suppressed critical behavior of fully connected graph states.
title Phase Transitions and Noise Robustness of Quantum Graph States
topic Quantum Physics
Statistical Mechanics
url https://arxiv.org/abs/2510.00548