Quantum thermal state preparation for near-term quantum processors
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arXiv
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| Main Authors: | , |
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| Format: | Preprint |
| Published: |
2025
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| _version_ | 1866918392609374208 |
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| author | Lloyd, Jerome Abanin, Dmitry A. |
| author_facet | Lloyd, Jerome Abanin, Dmitry A. |
| contents | Preparation of quantum thermal states of many-body systems is a key computational challenge for quantum processors, with applications in physics, chemistry, and classical optimization. We provide a simple and efficient algorithm for thermal state preparation, combining engineered bath resetting and modulated system-bath coupling to derive a quantum channel approximately satisfying quantum detailed balance relations. We show that the fixed point $\hatσ$ of the channel approximates the Gibbs state as $\|\hatσ-\hatσ_β\|\sim θ^2$, where $θ$ is the system-bath coupling and $\hatσ_β\propto e^{-β\hat H_S}$. We provide extensive numerics, for the example of the 2D Quantum Ising model, confirming that the protocol successfully prepares the thermal state throughout the finite-temperature phase diagram, including near the quantum phase transition. Simulations for free-fermion systems provide further evidence for the accuracy of the protocol for large system sizes in the weak-coupling limit. Our algorithm provides a path to efficient quantum simulation of quantum-correlated states at finite temperature with current and near-term quantum processors. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_21318 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Quantum thermal state preparation for near-term quantum processors Lloyd, Jerome Abanin, Dmitry A. Quantum Physics Quantum Gases Statistical Mechanics Strongly Correlated Electrons Preparation of quantum thermal states of many-body systems is a key computational challenge for quantum processors, with applications in physics, chemistry, and classical optimization. We provide a simple and efficient algorithm for thermal state preparation, combining engineered bath resetting and modulated system-bath coupling to derive a quantum channel approximately satisfying quantum detailed balance relations. We show that the fixed point $\hatσ$ of the channel approximates the Gibbs state as $\|\hatσ-\hatσ_β\|\sim θ^2$, where $θ$ is the system-bath coupling and $\hatσ_β\propto e^{-β\hat H_S}$. We provide extensive numerics, for the example of the 2D Quantum Ising model, confirming that the protocol successfully prepares the thermal state throughout the finite-temperature phase diagram, including near the quantum phase transition. Simulations for free-fermion systems provide further evidence for the accuracy of the protocol for large system sizes in the weak-coupling limit. Our algorithm provides a path to efficient quantum simulation of quantum-correlated states at finite temperature with current and near-term quantum processors. |
| title | Quantum thermal state preparation for near-term quantum processors |
| topic | Quantum Physics Quantum Gases Statistical Mechanics Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2506.21318 |