Boundary Perturbation Effects in Quantum Systems with Conserved Energy and Continuous Symmetry
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866915866103250944 |
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| author | Gao, Qucheng Chen, Xiao |
| author_facet | Gao, Qucheng Chen, Xiao |
| contents | We investigate one-dimensional systems with both energy conservation and a continuous symmetry, focusing on the impact of a boundary perturbation that breaks the continuous symmetry. Our study reveals two distinct dynamical phases: one in which the corresponding charge exhibits extensive fluctuations, and another where the charge remains conserved. These phases appear in both free and interacting models. We interpret this behavior through a boundary-induced pumping mechanism, which estimates the amplitude connecting two degenerate states from different charge sectors via a local charge-non-conserving operator. In the Floquet setting, we show that the frozen phase can survive at high driving frequencies but vanishes at low frequencies. This phenomenon is exact in free-fermion systems in the thermodynamic limit, but in interacting systems it appears only at finite system size. The emergence of the charge-frozen phase is attributed to effective energy conservation, and we demonstrate that this phase disappears when effective energy conservation is broken or replaced by other symmetries. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2502_16252 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Boundary Perturbation Effects in Quantum Systems with Conserved Energy and Continuous Symmetry Gao, Qucheng Chen, Xiao Quantum Physics Statistical Mechanics We investigate one-dimensional systems with both energy conservation and a continuous symmetry, focusing on the impact of a boundary perturbation that breaks the continuous symmetry. Our study reveals two distinct dynamical phases: one in which the corresponding charge exhibits extensive fluctuations, and another where the charge remains conserved. These phases appear in both free and interacting models. We interpret this behavior through a boundary-induced pumping mechanism, which estimates the amplitude connecting two degenerate states from different charge sectors via a local charge-non-conserving operator. In the Floquet setting, we show that the frozen phase can survive at high driving frequencies but vanishes at low frequencies. This phenomenon is exact in free-fermion systems in the thermodynamic limit, but in interacting systems it appears only at finite system size. The emergence of the charge-frozen phase is attributed to effective energy conservation, and we demonstrate that this phase disappears when effective energy conservation is broken or replaced by other symmetries. |
| title | Boundary Perturbation Effects in Quantum Systems with Conserved Energy and Continuous Symmetry |
| topic | Quantum Physics Statistical Mechanics |
| url | https://arxiv.org/abs/2502.16252 |