NTT Basic Research Laboratories, NTT Corporation, Morinosato-Wakamiya, Atsugi, Japan.
Science. 2012 Feb 17;335(6070):828-31. doi: 10.1126/science.1216697. Epub 2012 Jan 26.
The fractional quantum Hall (FQH) effect at filling factor ν = 5/2 has recently come under close scrutiny, as its ground state may possess quasi-particle excitations obeying nonabelian statistics, a property sought for topologically protected quantum operations. However, its microscopic origin remains unknown, and candidate model wave functions include those with undesirable abelian statistics. We report direct measurements of the electron spin polarization of the ν = 5/2 FQH state using resistively detected nuclear magnetic resonance. We find the system to be fully polarized, which unambiguously rules out the most likely abelian contender and lends strong support for the ν = 5/2 state being nonabelian. Our measurements reveal an intrinsically different nature of interaction in the first excited Landau level underlying the physics at ν = 5/2.
最近，填充因子 ν = 5/2 的分数量子霍尔（FQH）效应受到了密切关注，因为其基态可能具有服从非阿贝尔统计的准粒子激发，这是拓扑保护量子操作所需要的特性。然而，其微观起源仍不清楚，候选模型波函数包括那些具有不理想的阿贝尔统计的波函数。我们使用电阻检测核磁共振直接测量了 ν = 5/2 FQH 态的电子自旋极化。我们发现该系统完全极化，这明确排除了最有可能的阿贝尔竞争者，并为 ν = 5/2 态是非阿贝尔的提供了强有力的支持。我们的测量揭示了在 ν = 5/2 物理基础下的第一激发朗道能级中相互作用的本质上不同的性质。
