Chirality manipulation of ultrafast phase switches in a correlated CDW-Weyl semimetal

Abstract

Light engineering of correlated states in topological materials provides a new avenue of achieving exotic topological phases inaccessible by conventional tuning methods. Here we demonstrate a light control of correlation gaps in a model charge-density-wave (CDW) and polaron insulator (TaSe4)2I recently predicted to be an axion insulator. Our ultrafast terahertz photocurrent spectroscopy reveals a two-step, non-thermal melting of polarons and electronic CDW gap via the fluence dependence of a longitudinal circular photogalvanic current. This helicity-dependent photocurrent reveals continuous ultrafast phase switches from the polaronic state to the CDW (axion) phase, and finally to a hidden Weyl phase as the pump fluence increases. Additional distinctive attributes aligning with the light-induced switches include: the mode-selective coupling of coherent phonons to the polaron and CDW modulation, and the emergence of a non-thermal chiral photocurrent above the pump threshold of CDW-related phonons. The demonstrated ultrafast chirality control of correlated topological states here holds large potentials for realizing axion electrodynamics and advancing quantum-computing applications.

Two-dimensional coherent spectrum of high-spin models via a quantum computing approach

“…Understanding the magnetic properties of quantum materials is crucial for the development of new spintronic devices, quantum sensors, and quantum computer architectures [1][2][3][4][5][6][7][8][9][10]. Terahertz (THz) coherent spectroscopy [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] provides a powerful tool for characterizing the low-energy spin excitations of such materials, which are often inaccessible using other techniques.…”