Ultrafast laser-driven topological phase patterning

TL;DR

This paper demonstrates femtosecond laser-driven patterning of topological quantum states in WTe2, enabling ultrafast, spatially precise, and reversible control of phase transitions with potential for reconfigurable topological devices.

Contribution

It introduces a method for all-optical, spatially programmable control of topological phases using transient optical gratings and ultrafast microscopy.

Findings

Reversible phase transitions between Td and 1T* phases achieved.

Visualization of periodic heterostructures and phase front propagation.

Analysis of nanoscale optical phonon confinement.

Abstract

Microscopic and dynamic control over quantum states is essential for bridging fundamental studies of material properties to device function. Realizing such control at combined high spatial resolution and ultrafast temporal precision remains a major challenge. Here, we demonstrate femtosecond laser-driven patterning of topological quantum states in the Weyl semimetal WTe2. By engineering the excitation field into a transient optical grating, we spatially selectively and reversibly drive phase transitions between the topological Td and topologically trivial 1T* phases. Using ultrafast transmission electron microscopy, we directly visualize the formation of a periodic Td/1T* heterostructure, observe the propagation of a phase front, and analyze nanoscale confinement of coherently excited optical phonon modes. Our findings establish a platform for all-optical, spatially programmable, and reconfigurable control of quantum states, paving the way for optically addressable topological devices.