Inviter: 周发然 副研究员（9677）

Abstract:

Polaritons—hybrid quasiparticles arising from strong light–matter coupling—exhibit extreme electromagnetic confinement. When combined with the high tunability and versatile stacking of two-dimensional quantum materials, they provide unprecedented opportunities to engineer emergent quantum phases [1,2].

In this talk, I will present our recent advances in the infrared nano-optics of quantum materials, enabled by a custom-developed cryogenic scattering-type scanning near-field optical microscope (s-SNOM). I will first introduce the design and capabilities of our home-built s-SNOM platform. I will then demonstrate how the plasmonic response is highly sensitive to the underlying moiré potential landscape, allowing us to challenge the widely accepted notion of moiré ferroelectricity [3,4]. Finally, I will demonstrate that hyperbolic phonon polaritons can be harnessed to enhance vacuum fluctuations, through which we successfully engineer the superfluid density of adjacent superconducting layers [5]. These results establish polaritons as a powerful platform for probing, controlling, and designing quantum phases in vdW heterostructures.

[1] DN. Basov et al., Science 354, aag1992 (2016).
[2] S. Zhang et al., Phys. Rev. Lett. 136, 136904 (2026).
[3] S. Zhang et al., Phys. Rev. X 15, 011019 (2025).
[4] S. Zhang et al., Nature Commun. 14, 6200 (2023).
[5] I. Keren†, T. A. Webb†, S. Zhang† et al., Nature 650, 864 (2025).

About the speaker：
Shuai Zhang is an assistant professor in the Department of Physics at Fudan University. He received his Ph.D. from Fudan University and subsequently worked as a postdoctoral researcher and associate research scientist at Columbia University. His research focuses on infrared and terahertz nano-optics of quantum materials. He has developed advanced cryogenic near-field optical microscopy techniques to probe and control quantum phenomena at the nanoscale.