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arXiv 1312.6367cond-mat.mes-hallcond-mat.str-el
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一维超导体中相互作用费米子拓扑指数的散射矩阵公式

A scattering matrix formulation of the topological index of interacting fermions in one-dimensional superconductors

Dganit Meidan, Alessandro Romito, Piet W. Brouwer

摘要:

我们构造了一个散射矩阵公式,用于在存在相互作用的情况下对具有有效时间反演对称性的一维超导体进行拓扑分类。对于闭几何,Fidkowski和Kitaev证明了这样的系统有一个$\mathbb{Z}_8$拓扑分类。我们表明,在弱耦合极限下,这些系统在零温度下保留了么正散射矩阵,其拓扑指数由Andreev反射矩阵的迹给出,即$\mbox{tr}\, r_{\rm he}$。对于交互,$\mbox{tr}\, r_{\rm he}$一般采用值$0$、$\pm 1$、$\pm 2$、$\pm 3$和$\pm 4$的有限集合。我们发现,两个拓扑等价的阶段与$\mbox{tr}\, r_{\rm he} = \pm 4$支持紧急多体端态,我们确定是一个拓扑保护的近藤共振。相空间中连接这些等效相的路径穿过非费米液体固定点,在该固定点处发展多通道近藤效应。我们的研究结果连接的拓扑指数的传输性能,从而突出了在一维相互作用的拓扑相位的实验签名。

英文摘要:

We construct a scattering matrix formulation for the topological classification of one-dimensional superconductors with effective time reversal symmetry in the presence of interactions. For a closed geometry, Fidkowski and Kitaev have shown that such systems have a $\mathbb{Z}_8$ topological classification. We show that in the weak coupling limit, these systems retain a unitary scattering matrix at zero temperature, with a topological index given by the trace of the Andreev reflection matrix, $\mbox{tr}\, r_{\rm he}$. With interactions, $\mbox{tr}\, r_{\rm he}$ generically takes on the finite set of values $0$, $\pm 1$, $\pm 2$, $\pm 3$, and $\pm 4$. We show that the two topologically equivalent phases with $\mbox{tr}\, r_{\rm he} = \pm 4$ support emergent many-body end states, which we identify to be a topologically protected Kondo-like resonance. The path in phase space that connects these equivalent phases crosses a non-fermi liquid fixed point where a multiple channel Kondo effect develops. Our results connect the topological index to transport properties, thereby highlighting the experimental signatures of interacting topological phases in one dimension.

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