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Researchers have demonstrated that monolayer WSe2 can host Wigner crystals (lattices formed purely of electrons) without requiring external magnetic fields, and have used exciton spectroscopy to probe their internal dynamics for the first time. They discovered "Wigner polarons," quasiparticles formed when the electron lattice is locally distorted by interactions with excitons, revealing both static and dynamic properties of these quantum structures. The team achieved all-optical control of the Wigner crystal's spin properties and demonstrated optical melting of the crystal, observing distinct responses between static order and dynamic excitations.
Why it matters
This work provides a new experimental platform and measurement technique to study strongly correlated electron systems, addressing a decades-old challenge in accessing the internal dynamics of Wigner crystals. The ability to optically control and manipulate these quantum phases could enable ultrafast optical switches and advance understanding of correlation-driven quantum phase transitions with potential applications in quantum materials and devices.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
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Abstract: Wigner crystals, lattices made purely of electrons, are a quintessential paradigm of studying correlation-driven quantum phase transitions. Despite decades of research, the internal dynamics of Wigner crystals has remained extremely challenging to access, with most experiments probing only static order or collective motion. Here, we establish monolayer WSe2 as a new materials platform to host zero-field Wigner crystals and then demonstrate that exciton spectroscopy provides a direct means to probe both static and dynamic properties of these electron lattices. We uncover striking optical resonances that we identify as Wigner polarons, quasiparticles formed when the electron lattice is locally distorted by exciton-Wigner crystal coupling. We further achieve all-optical control of spins in the Wigner crystal, directly probing valley-dependent Wigner polaron scattering well above the magnetic ordering temperature and in the absence of any external magnetic field. Finally, we demonstrate optical melting of the Wigner crystal and observe intriguingly different responses of the umklapp (static) and Wigner polaron (dynamic) resonances to optical excitation. Our results open up exciting new avenues for elucidating electron dynamics and achieving ultrafast optical control of interaction-driven quantum phase transitions in strongly correlated electron systems.
Source: Wigner polarons reveal Wigner crystal dynamics in a monolayer semiconductor