Fano resonance through Higgs bound states in tunneling of Nambu-Goldstone modes
Fano resonance through Higgs bound states in tunneling of Nambu-Goldstone modes
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DOI：
10.1103/physreva.92.043610
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发表时间：
2015-03
影响因子：
2.9
通讯作者：
T. Nakayama;I. Danshita;T. Nikuni;S. Tsuchiya
中科院分区：
文献类型：
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作者：
T. Nakayama;I. Danshita;T. Nikuni;S. Tsuchiya
我们研究光学晶格中超流体玻色气体与势垒的集体模式。我们假设系统处于相应填充的莫特绝缘体的量子相变附近，其中出现的粒子空穴对称性产生两种类型的集体模式，即无间隙南部-戈德斯通（NG）相模式和有间隙希格斯振幅模式。我们考虑两种势垒：一种不破坏粒子空穴对称性，另一种则破坏。在存在前一个势垒的情况下，我们发现希格斯束缚态的结合能低于体希格斯间隙并且位于势垒周围。我们分析了两个势垒的 NG 模式的隧道特性，表明后者将希格斯束缚态与 NG 模式耦合，导致由束缚态介导的法诺共振。由于基础场论的普遍性，预计希格斯束缚态也可能存在于其他具有粒子空穴对称性和连续对称性自发破缺的凝聚态物质系统中，例如量子二聚体反铁磁体、超导体和电荷密度波材料。
We study collective modes of superfluid Bose gases in optical lattices combined with potential barriers. We assume that the system is in the vicinity of the quantum phase transition to a Mott insulator at a commensurate filling, where emergent particle-hole symmetry gives rise to two types of collective mode, namely a gapless Nambu-Goldstone (NG) phase mode and a gapful Higgs amplitude mode. We consider two kinds of potential barrier: One does not break the particle-hole symmetry while the other does. In the presence of the former barrier, we find Higgs bound states that have binding energies lower than the bulk Higgs gap and are localized around the barrier. We analyze tunneling properties of the NG mode incident to both barriers to show that the latter barrier couples the Higgs bound states with the NG mode, leading to Fano resonance mediated by the bound states. Thanks to the universality of the underlying field theory, it is expected that Higgs bound states may be present also in other condensed matter systems with a particle-hole symmetry and spontaneous breaking of a continuous symmetry, such as quantum dimer antiferromagnets, superconductors, and charge-density-wave materials.