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arXiv 2003.08864cond-mat.quant-gas
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耗散Fermi-哈伯德模型中相互作用诱导的动力学$\mathcal{PT}$对称性破缺

Interaction induced dynamical $\mathcal{PT}$ symmetry breaking in dissipative Fermi-Hubbard models

Lei Pan, Xueliang Wang, Xiaoling Cui, Shu Chen

摘要:

研究了一维耗散Fermi-哈伯德模型的动力学性质,该模型由Lindblad主方程描述.如果对系统附加一个增益项,则相应的非厄米有效哈密顿量具有宇称-时间($\mathcal{PT}$)对称性。通过精确求解具有固定耗散的二位林德布拉德方程,我们发现当相互作用超过阈值时,重标度密度矩阵的动力学表现出不稳定性,这种不稳定性可以用非厄米有效哈密顿量来等价描述.这种不稳定性也观察到在多站点系统和密切相关的$\mathcal{PT}$对称性破缺伴随着外观的复杂的本征值的有效哈密顿量。此外,我们还揭示了反铁磁Mott相的动力学不稳定性来自于高激发带的$\mathcal{PT}$对称性破缺,而非厄米哈伯德模型在强相互作用区的低能有效模型总是厄米模型.我们还提供了一个定量的时间估计的观测动力学$\mathcal{PT}$对称性破缺,可以在实验中探索。

英文摘要:

We investigate the dynamical properties of one-dimensional dissipative Fermi-Hubbard models, which are described by the Lindblad master equations with site-dependent jump operators. The corresponding non-Hermitian effective Hamiltonians with pure loss terms possess parity-time ($\mathcal{PT}$) symmetry if we compensate the system additionally an overall gain term. By solving the two-site Lindblad equation with fixed dissipation exactly, we find that the dynamics of rescaled density matrix shows an instability as the interaction increases over a threshold, which can be equivalently described in the scheme of non-Hermitian effective Hamiltonians. This instability is also observed in multi-site systems and closely related to the $\mathcal{PT}$ symmetry breaking accompanied by appearance of complex eigenvalues of the effective Hamiltonian. Moreover, we unveil that the dynamical instability of the anti-ferromagnetic Mott phase comes from the $\mathcal{PT}$ symmetry breaking in highly excited bands, although the low-energy effective model of the non-Hermitian Hubbard model in the strongly interacting regime is always Hermitian. We also provide a quantitative estimation of the time for the observation of dynamical $\mathcal{PT}$ symmetry breaking which could be probed in experiments.

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