Journal Article

Light-Driven Raman Coherence as a Nonthermal Route to Ultrafast Topology Switching in a Dirac Semimetal

Mootz, M., Li, Q., Kim, R. H. J., Lozano, P. M., Perakis, I. E., Wang, L.-L., Liu, Z., Wang, J., Gu, G. D., Luo, L., Yao, Y., Ho, K. M., Vaswani, C., Huang, C., Cheng, D., Mudiyanselage, D. H., Song, B.

2020

Overview

A grand challenge underlies the entire field of topology-enabled quantum logic and information science: how to establish topological control principles driven by quantum coherence and understand the time dependence of such periodic driving. Here we demonstrate a few-cycle THz-pulse-induced phase transition in a Dirac semimetalZrTe5that is periodically driven by vibrational coherence due to excitation of the lowest Raman active mode. Above a critical THz-pump field threshold, there emerges a long-lived metastable phase, approximately 100 ps, with unique Raman phonon-assisted topological switching dynamics absent for optical pumping. The switching also manifests itself by distinct features: nonthermal spectral shape, relaxation slowing near the Lifshitz transition where the critical Dirac point occurs, and diminishing signals at the same temperature that the Berry-curvature-induced anomalous Hall effect magnetoresistance vanishes. These results, together with first-principles modeling, identify a mode-selective Raman coupling that drives the system from strong to weak topological insulators with a Dirac semimetal phase established at a critical atomic displacement controlled by the phonon coherent pumping. Harnessing of vibrational coherence can be extended to steer symmetry-breaking transitions, i.e., Dirac to Weyl ones, with implications for THz topological quantum gate and error correction applications.

• Publisher: American Physical Society,American Physical Society (APS)
• Subject: Broken symmetry / Coherence / CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY / Electronics / Elementary excitations / Energy consumption / Energy costs / Energy dissipation / Equilibrium methods / Error correction / First principles / Hall effect / Magnetoresistance / Magnetoresistivity / Metalloids / Metastable phases / Optical pumping / Phase transitions / Phonons / Principles / Quantum computing / Quantum phenomena / Qubits (quantum computing) / Switching / Terahertz techniques / Time dependence / topolgical phases of matter / Topological insulators / topological materials / Topology / ultrafast pump-probe spectroscopy