Generic “unnecessary” quantum critical points with minimal degrees of freedom
Generic “unnecessary” quantum critical points with minimal degrees of freedom
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DOI：
10.1103/physrevb.101.035118
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发表时间：
2019-07
影响因子：
3.7
通讯作者：
Chao-Ming Jian;Cenke Xu
中科院分区：
文献类型：
--
作者：
Chao-Ming Jian;Cenke Xu
我们探索一般的“不必要的”量子临界点与最小的自由度。这些量子临界点可以通过足够强的哈密顿量的量子允许的变形来避免，但是这些变形在量子临界点处的特定阈值以下是不相关的扰动。因此，这些量子临界点是不必要的，但也是未微调的（通用的）。先前已知的这种通用的不必要的量子临界点的例子涉及至少八个狄拉克费米子在二维和三维空间。在这项工作中，我们寻求的例子一般不必要的量子临界点的最小自由度。特别是，在三维空间中，我们确定了两个这样的通用不必要的量子临界点的例子。第一个例子发生在3d相互作用的拓扑绝缘体中，在红外线极限下，它可以用两个（3+1）d无质量的狄拉克费米子来描述;第二个例子发生在3d拓扑超导体中，它可以用一个（3+1）d无质量的狄拉克费米子来描述。
We explore generic ``unnecessary'' quantum critical points with minimal degrees of freedom. These quantum critical points can be avoided with strong enough symmetry-allowed deformations of the Hamiltonian, but these deformations are irrelevant perturbations below certain threshold at the quantum critical point. These quantum critical points are hence unnecessary, but also unfine-tuned (generic). The previously known examples of such generic unnecessary quantum critical points involve at least eight Dirac fermions in both two and three spatial dimensions. In this work we seek for examples of generic unnecessary quantum critical points with minimal degrees of freedom. In particular, in three-dimensional space, we identify two examples of such generic unnecessary quantum critical points. The first example occurs in a $3d$ interacting topological insulator, and it is described by two $(3+1)d$ massless Dirac fermions in the infrared limit; the second example occurs in a $3d$ topological superconductor, and it is formally described by only one $(3+1)d$ massless Dirac fermion.