Exact Current Fluctuations in a Tight-Binding Chain with Dephasing Noise
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866910224089088000 |
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| author | Ishiyama, Taiki Fujimoto, Kazuya Sasamoto, Tomohiro |
| author_facet | Ishiyama, Taiki Fujimoto, Kazuya Sasamoto, Tomohiro |
| contents | The full counting statistics (FCS) of current has long provided fundamental insights into nonequilibrium systems. Recently, the FCS in quantum many-body systems has attracted growing attention, driven by rapid experimental progress in measuring current fluctuations. Nevertheless, for diffusive quantum many-body dynamics, the FCS of current has yet to be obtained exactly. In this Letter, we present the first exact solution for the FCS of current in a diffusive quantum many-body system, specifically a tight-binding chain with dephasing noise. By leveraging the system's SU(2) symmetry and a mapping to the one-dimensional Hubbard model, we derive an exact Fredholm determinant representation for the moment generating function of the time-integrated current. Our long-time asymptotic analysis shows that the cumulant generating function, and hence the corresponding large-deviation function, exhibit diffusive scaling for any nonzero dephasing. We compare our theoretical predictions with experimentally measured current variance and find consistent diffusive scaling. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_06989 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Exact Current Fluctuations in a Tight-Binding Chain with Dephasing Noise Ishiyama, Taiki Fujimoto, Kazuya Sasamoto, Tomohiro Statistical Mechanics Quantum Gases Mathematical Physics Quantum Physics The full counting statistics (FCS) of current has long provided fundamental insights into nonequilibrium systems. Recently, the FCS in quantum many-body systems has attracted growing attention, driven by rapid experimental progress in measuring current fluctuations. Nevertheless, for diffusive quantum many-body dynamics, the FCS of current has yet to be obtained exactly. In this Letter, we present the first exact solution for the FCS of current in a diffusive quantum many-body system, specifically a tight-binding chain with dephasing noise. By leveraging the system's SU(2) symmetry and a mapping to the one-dimensional Hubbard model, we derive an exact Fredholm determinant representation for the moment generating function of the time-integrated current. Our long-time asymptotic analysis shows that the cumulant generating function, and hence the corresponding large-deviation function, exhibit diffusive scaling for any nonzero dephasing. We compare our theoretical predictions with experimentally measured current variance and find consistent diffusive scaling. |
| title | Exact Current Fluctuations in a Tight-Binding Chain with Dephasing Noise |
| topic | Statistical Mechanics Quantum Gases Mathematical Physics Quantum Physics |
| url | https://arxiv.org/abs/2504.06989 |