Non-ergodic behaviour of clean Bose-Hubbard chains
Non-ergodic behaviour of clean Bose-Hubbard chains
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发表时间：
2020-05
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通讯作者：
A. Russomanno;Michele Fava;R. Fazio
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作者：
A. Russomanno;Michele Fava;R. Fazio
我们研究了干净 Bose-Hubbard 链中小跳跃强度的遍历性破坏。通过本征态的半链纠缠熵、平均能级间距比和佩雷斯·洛施密特回波的动力学等指标，我们看到非遍历状态的明显存在。我们发现这种遍历性破坏不符合多体定位范式，因为本征态的平均半链纠缠熵遵循体积定律。这种遍历性破坏似乎与在小跳变和有限系统尺寸下以准边生成多重态组织的频谱无关，因此原则上它也可以适用于较大的系统尺寸。我们发现，时间上的一些不平衡振荡可能标志着空间中玻璃行为的存在，这些振荡可以通过单个对称破缺双峰的动力学得到很好的描述，并且可以通过微扰有效 XXZ 模型很好地捕获。我们证明这些振荡的幅度在大尺寸极限下消失。
We study ergodicity breaking in the clean Bose-Hubbard chain for small hopping strength. We see the clear existence of a non-ergodic regime by means of indicators as the half-chain entanglement entropy of the eigenstates, the average level spacing ratio and the dynamics of the Peres Loschmidt echo. We find that this ergodicity breaking falls out the many-body localization paradigm because the average half-chain entanglement entropy of the eigenstates obeys volume law. This ergodicity breaking appears unrelated to the spectrum being organized in quasidegenerate multiplets at small hopping and finite system sizes, so in principle it can survive also for larger system sizes. We find that some imbalance oscillations in time which could mark the existence of a glassy behaviour in space are well described by the dynamics of a single symmetry-breaking doublet and well captured by a perturbative effective XXZ model. We show that the amplitude of these oscillations vanishes in the large-size limit.