González-Cuadra D, Dauphin A, Grzybowski P R, Lewenstein M, Bermudez A
ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Avinguda Carl Friedrich Gauss 3, 08860 Castelldefels (Barcelona), Spain.
Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland.
Phys Rev Lett. 2020 Dec 31;125(26):265301. doi: 10.1103/PhysRevLett.125.265301.
We study the Z_{2} Bose-Hubbard model, a chain of interacting bosons the tunneling of which is dressed by a dynamical Z_{2} field. The interplay between spontaneous symmetry breaking (SSB) and topological symmetry protection gives rise to interesting fractional topological phenomena when the system is doped to certain incommensurate fillings. In particular, we hereby show how topological defects in the Z_{2} field can appear in the ground state, connecting different SSB sectors. These defects are dynamical and can travel through the lattice carrying both a topological charge and a fractional particle number. In the hardcore limit, this phenomenon can be understood through a bulk-defect correspondence. Using a pumping argument, we show that it survives also for finite interactions, demonstrating how boson fractionalization induced by topological defects can occur in strongly correlated bosonic systems. Our results indicate the possibility of observing this phenomenon, which appears for fermionic matter in solid-state and high-energy physics, using ultracold atomic systems.
我们研究了Z₂玻色-哈伯德模型，这是一个由相互作用的玻色子组成的链，其隧穿由一个动态Z₂场修饰。当系统被掺杂到某些非 commensurate填充时，自发对称性破缺（SSB）和拓扑对称性保护之间的相互作用会产生有趣的分数拓扑现象。特别是，我们在此展示了Z₂场中的拓扑缺陷如何能出现在基态中，连接不同的SSB扇区。这些缺陷是动态的，并且可以携带拓扑电荷和分数粒子数穿过晶格。在硬核极限下，这种现象可以通过体-缺陷对应来理解。使用一个泵浦论证，我们表明它在有限相互作用下也存在，证明了由拓扑缺陷引起的玻色子分数化如何能在强关联玻色子系统中发生。我们的结果表明，利用超冷原子系统有可能观察到这种现象，这种现象在固态和高能物理中的费米子物质中出现。
