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arXiv · 2504.20150

Shot noise in strongly correlated double quantum spin Hall edges

Andreas Tsantilas·Trithep Devakul·Julian May-Mann
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Abstract

We consider the effects of interactions on the edges of ``double" quantum spin Hall insulators (DQSHIs), motivated by recent experiments on moir\'e twisted metal dichalcogenides. Without interactions, a DQSHI can be understood as two copies of a conventional quantum spin Hall insulator. If interactions are present and $s^z$-spin is conserved, we show that there are two possible phases for the DQSHI edge. First is a weakly correlated edge which has two pairs of helical modes and is adiabatically equivalent to two conventional quantum spin Hall edges. Second is a strongly correlated edge with only one pair of helical modes. The strongly correlated edge also has a gap to single electrons, but is gapless to pairs of electrons. In a quantum point contact geometry, this single-electron gap leads to a Fano factor of $2$ in shot noise measurements, compared to a Fano factor of $1$ for a weakly correlated edge.

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Andreas Tsantilas, Trithep Devakul, Julian May-Mann. 2025-04-28. Shot noise in strongly correlated double quantum spin Hall edges. https://arxiv.org/abs/2504.20150

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