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arXiv 2202.00490cond-mat.mes-hall
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分数量子霍尔相位拓扑边量子数的确定

Determination of topological edge quantum numbers of fractional quantum Hall phases

Saurabh Kumar Srivastav, Ravi Kumar, Christian Spånslätt, K. Watanabe, T. Taniguchi, Alexander D. Mirlin, Yuval Gefen, Anindya Das

摘要:

为了确定具有反向传播(CP)的下游($N_d$)和上游($N_u$)边缘模的分数量子霍尔(HHH)态的拓扑量子数,研究存在和不存在边缘模平衡时的量子输运是关键.虽然达到非平衡状态对于电荷传输是具有挑战性的,但我们在此针对热霍尔电导$G_{Q}$,其纯粹由边缘量子数$N_d$和$N_u$控制。我们的实验装置是用hBN封装的石墨门控单层石墨烯器件实现的。对于高达$35mK$的温度,我们在$ν= $ 2/3和3/5(具有CP模式)下测量的$G_{Q}$与非平衡状态$(N_d + N_u)κ_{0}T$的量化值相匹配,其中$κ_{0}T$是$G_{Q}$的量子。随着温度的升高,$G_{Q}$降低并最终达到平衡状态的值$|N_d - N_u|κ_{0}T$。相比之下,在$ν= $ 1/3和2/5(没有CP模式)下,$G_Q$在$N_dκ_{0}T$下保持稳健量化,与温度无关。因此,通过测量$G_{Q}$在两个区域的量子化值,我们确定了边缘量子数,这为寻找奇异的非阿贝尔量子态的拓扑序开辟了一条新的途径。

英文摘要:

To determine the topological quantum numbers of fractional quantum Hall (FQH) states hosting counter-propagating (CP) downstream ($N_d$) and upstream ($N_u$) edge modes, it is pivotal to study quantized transport both in the presence and absence of edge mode equilibration. While reaching the non-equilibrated regime is challenging for charge transport, we target here the thermal Hall conductance $G_{Q}$, which is purely governed by edge quantum numbers $N_d$ and $N_u$. Our experimental setup is realized with a hBN encapsulated graphite gated monolayer graphene device. For temperatures up to $35mK$, our measured $G_{Q}$ at $ν= $ 2/3 and 3/5 (with CP modes) match the quantized values of non-equilibrated regime $(N_d + N_u)κ_{0}T$, where $κ_{0}T$ is a quanta of $G_{Q}$. With increasing temperature, $G_{Q}$ decreases and eventually takes the value of equilibrated regime $|N_d - N_u|κ_{0}T$. By contrast, at $ν= $1/3 and 2/5 (without CP modes), $G_Q$ remains robustly quantized at $N_dκ_{0}T$ independent of the temperature. Thus, measuring the quantized values of $G_{Q}$ at two regimes, we determine the edge quantum numbers, which opens a new route for finding the topological order of exotic non-Abelian FQH states.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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