无序导致 Mott 态阻尼局域化激发的出现
Emergence of damped-localized excitations of the Mott state due to disorder
AI总结：
本研究利用场论方法探讨无序对零温 Bose-Hubbard 模型 Mott 绝缘态低能激发的影响，发现无序增加了准粒子和准空穴的有效质量，并产生空间指数衰减的阻尼局域化态，对应于 Bose-glass 相的单粒子激发。
摘要：
深光晶格势阱中超冷玻色量子气体的一个关键方面是实现强相互作用的 Mott 绝缘相。该相的许多特性已被充分理解，但关于随机外势对其有能隙的准粒子和准空穴低能激发的影响却知之甚少。在本研究中，我们探讨了无序对由 Bose-Hubbard 模型描述的零温 Mott 绝缘态激发的影响。利用场论方法，我们得到了谱函数无序系综平均的重求和表达式。对其分析表明，无序导致准粒子和准空穴激发的有效质量均增加。此外，它还导致了阻尼态的出现，这些阻尼态在空间传播过程中呈指数衰减，并在无序强度与相互作用可比拟时主导整个能带。我们认为，这种阻尼局域化态对应于 Bose-glass 相的单粒子激发。
英文摘要：
A key aspect of ultracold bosonic quantum gases in deep optical lattice potential wells is the realization of the strongly interacting Mott insulating phase. Many characteristics of this phase are well understood, however little is known about the effects of a random external potential on its gapped quasiparticle and quasihole low-energy excitations. In the present study we investigate the effect of disorder upon the excitations of the Mott insulating state at zero temperature described by the Bose-Hubbard model. Using a field-theoretical approach we obtain a resummed expression for the disorder ensemble average of the spectral function. Its analysis shows that disorder leads to an increase of the effective mass of both quasiparticle and quasihole excitations. Furthermore, it yields the emergence of damped states, which exponentially decay during propagation in space and dominate the whole band when disorder becomes comparable to interactions. We argue that such damped-localized states correspond to single-particle excitations of the Bose-glass phase.
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