Exciton Superposition across Moiré States in a Semiconducting Moiré Superlattice

Zhen Lian; Dongxue Chen; Yuze Meng; Xiaotong Chen; Ying Su; Rounak Banerjee; Takashi Taniguchi; Kenji Watanabe; Sefaattin Tongay; Chuanwei Zhang; Yong-Tao Cui; Su-Fei Shi

Article Exciton Superposition across Moiré States in a Semiconducting Moiré Superlattice

Zhen Lian ; Dongxue Chen ; Yuze Meng ; Xiaotong Chen ; Ying Su ; Rounak Banerjee ; Takashi Taniguchi (National Institute for Materials Science) ; Kenji Watanabe (National Institute for Materials Science) ; Sefaattin Tongay ; Chuanwei Zhang ; Yong-Tao Cui ; Su-Fei Shi

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Zhen Lian, Dongxue Chen, Yuze Meng, Xiaotong Chen, Ying Su, Rounak Banerjee, Takashi Taniguchi, Kenji Watanabe, Sefaattin Tongay, Chuanwei Zhang, Yong-Tao Cui, Su-Fei Shi. Exciton Superposition across Moiré States in a Semiconducting Moiré Superlattice. Nature Communications. 2023, 14 (1), 5042.

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Moiré superlattices of semiconducting transitional metal dichalcogenides (TMDCs) enable unprecedented spatial control of electron wavefunction in an artificial lattice with periodicities more than ten times that of atomic crystals, leading to emerging quantum states with fascinating electronic and optical properties. The breaking of translational symmetry further introduces a new degree of freedom inside each moiré unit cell: high symmetry points of energy minima called moiré sites, behaving as spatially separated quantum wells. The superposition of a quasiparticle’s wavefunction between different moiré sites will enable a new platform for quantum information processing but is hindered by the suppressed electron tunneling between moiré sites. Here we demonstrate the superposition between two moiré sites by constructing an angle-aligned trilayer WSe2/monolayer WS2 moiré heterojunction. The two moiré sites with energy minimum allow the formation of two different interlayer excitons, with the hole residing in either moiré site of the first WSe2 layer interfacing the WS2 layer and the electron in the third WSe2 layer. An external electric field can drive the hybridization of either of the interlayer excitons with the intralayer excitons in the third WSe2 layer, realizing the continuous tuning of interlayer exciton hopping between two moiré sites. Therefore, a superposition of the two interlayer excitons localized at different moiré sites can be realized, which can be resolved in the electric-field-dependent optical reflectance spectra, distinctly different from that of the natural trilayer WSe2 in which the moiré modulation is absent. Our study illustrates a strategy of harnessing the new moiré site degree of freedom for quantum information science and sets up the stage for exciting opportunities of “moirétronics”.

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