Wide-scale adoption of quantum computing and information recording with ultra-low heat production requires building devices in which fragile quantum states are protected from their noisy environments and minimizing energy consumption. One approach is based on
“symmetry-protected” topological quasiparticles that are theoretically immune to noise and enable spin and/or chirality switching by externally-driven coherent lattice and/or electronic motion with minimum energy loss. A new, light-induced symmetry switch changes the crystal symmetry, and photogenerates a giant, low-dissipation current with exceptional ballistic transport protected by symmetry. Such topological control principles are demonstrated using near-infrared pulse to drive coherent infrared phonons and, in turn, induce a topological phase transition from Dirac to Weyl semimetal states in ZrTe5. Experimental results, combined with first-principles modeling, indicate two pairs of Weyl points are dynamically created by mode-selective phonon pumping to create the broken inversion symmetry. Such phononic terahertz control breaks ground for coherent manipulation of Weyl nodes and robust quantum transport without application of static electric or magnetic fields. The discovery holds great promise for spintronics, topological effect transistors, and quantum computing.
The research is further discussed in the paper, L. Luo, D. Cheng, B. Song, L.-L. Wang, C. Vaswani, P. M. Lozano, G. Gu, C. Huang, R. H. J. Kim, Z. Liu, J.-M. Park, Y. Yao, K.-M. Ho, I. E. Perakis, Q. Li and J. Wang, “A Light-induced Phononic Symmetry Switch and Giant Dissipationless Topological Photocurrent in ZrTe5” Nature Materials, 10.1038/s41563-020-00882-4 (2020).