论文标题
$ν= 2/3 $分数量子厅状态在量子点接触中的半数电导高原
Half-integer conductance plateau at the $ν= 2/3$ fractional quantum Hall state in a quantum point contact
论文作者
论文摘要
$ν= 2/3 $分数量子厅状态是主要laughlin $ν= 1/3 $状态的孔偶联状态。我们通过在GAAS/ALGAA异质结构上制造的量子点接触来调查边缘状态的传播，旨在具有巨大的限制电势。当应用小但有限的偏置时，我们会观察到一个中间电导高原，$ g = 0.5 \ frac {e^2} {h} $。在多个QPC中观察到该平台，并在大量磁场，栅极电压和源排出偏置范围内持续存在，从而使其成为强大的特征。使用一个简单的模型，该模型考虑了反向带电的边缘模式之间的散射和策略，我们发现该半数量化的平台可以与内部反向物的-1/3边缘模式完全反射时，而外整数模式已完全传输。在具有较软限制电势的不同异质结构上制造的QPC中，我们相反观察一个中间电导平台，$ g = \ frac {1} {1} {3} {3} \ frac {e^2} {h h} {h} $。这些结果为$ν= 2/3 $的模型提供了支持，其中边缘从具有内部上游的-1/3电荷模式和外部下游整数模式到具有两个下游1/3电荷模式的结构的结构进行了转换，当时限制电势从锋利的敏感到软障碍和无序效果。
The $ν= 2/3$ fractional quantum Hall state is the hole-conjugate state to the primary Laughlin $ν= 1/3$ state. We investigate transmission of edge states through quantum point contacts fabricated on a GaAs/AlGaAs heterostructure designed to have a sharp confining potential. When a small but finite bias is applied, we observe an intermediate conductance plateau with $G = 0.5 \frac{e^2}{h}$. This plateau is observed in multiple QPCs, and persists over a significant range of magnetic field, gate voltage, and source-drain bias, making it a robust feature. Using a simple model which considers scattering and equilibration between counterflowing charged edge modes, we find this half-integer quantized plateau to be consistent with full reflection of an inner counterpropagating -1/3 edge mode while the outer integer mode is fully transmitted. In a QPC fabricated on a different heterostructure which has a softer confining potential, we instead observe an intermediate conductance plateau at $G = \frac{1}{3} \frac{e^2}{h}$. These results provide support for a model at $ν= 2/3$ in which the edge transitions from a structure having an inner upstream -1/3 charge mode and outer downstream integer mode to a structure with two downstream 1/3 charge modes when the confining potential is tuned from sharp to soft and disorder prevails.
