@article{cdc966ab39ca4cd6b1749fbc880b69c2,
title = "Causal structure of interacting Weyl fermions in condensed matter systems",
abstract = "The spacetime light cone is central to the definition of causality in the theory of relativity. Recently, links between relativistic and condensed matter physics have been uncovered, where relativistic particles can emerge as quasiparticles in the energy-momentum space of matter. Here, we unveil an energy-momentum analogue of the spacetime light cone by mapping time to energy, space to momentum, and the light cone to the Weyl cone. We show that two Weyl quasiparticles can only interact to open a global energy gap if they lie in each other{\textquoteright}s energy-momentum dispersion cones–analogous to two events that can only have a causal connection if they lie in each other{\textquoteright}s light cones. Moreover, we demonstrate that the causality of surface chiral modes in quantum matter is entangled with the causality of bulk Weyl fermions. Furthermore, we identify a unique quantum horizon region and an associated {\textquoteleft}thick horizon{\textquoteright} in the emergent causal structure.",
author = "Chiu, {Wei Chi} and Guoqing Chang and Gennevieve Macam and Ilya Belopolski and Huang, {Shin Ming} and Robert Markiewicz and Yin, {Jia Xin} and Cheng, {Zi Jia} and Lee, {Chi Cheng} and Chang, {Tay Rong} and Chuang, {Feng Chuan} and Xu, {Su Yang} and Hsin Lin and Hasan, {M. Zahid} and Arun Bansil",
note = "Funding Information: We thank Justin Ripley for a helpful discussion. G.C. acknowledges the support of the National Research Foundation, Singapore under its Fellowship Award (NRF-NRFF13-2021-0010) and the Nanyang Assistant Professorship grant from Nanyang Technological University. The work at Northeastern University was supported by the Air Force Office of Scientific Research under award number FA9550-20-1-0322, and it benefited from the computational resources of Northeastern University{\textquoteright}s Advanced Scientific Computation Center (ASCC) and the Discovery Cluster. M.Z.H. was supported by the US DOE under the Basic Energy Sciences program (grant number DOE/BES DE-FG-02-05ER46200). S.M.H. is supported by the NSTC-AFOSR Taiwan program on Topological and Nanostructured Materials, Grant No. 110-2124-M-110-002-MY3. C.-C.L. acknowledges the National Science and Technology Council (NSTC) of Taiwan for financial support under Contract No. 110-2112-M-032-016-MY2. F.C.C. acknowledges the support by the National Center for Theoretical Sciences and the Ministry of Science and Technology of Taiwan under grant no. MOST-110-2112-M-110-013-MY3. S.-Y.X. acknowledges the support of the Center for the Advancement of Topological Semimetals (CATS), an Energy Frontier Research Center (EFRC) funded by the US Department of Energy (DOE) Office of Science, through the Ames Laboratory under contract DE-AC0207CH11358 (fabrication and measurements), the STC Center for Integrated Quantum Materials (CIQM), National Science Foundation (NSF) award no. ECCS-2025158 (data analysis), and the Corning Fund for Faculty Development. H.L. acknowledges the support by the National Science and Technology Council (NSTC) in Taiwan under grant number MOST 111-2112-M-001-057-MY3. T.-R.C. was supported by the Young Scholar Fellowship Program from the Ministry of Science and Technology (MOST) in Taiwan, under a MOST grant for the Columbus Program MOST110-2636-M-006-016, the National Cheng Kung University, Taiwan, and National Center for Theoretical Sciences, Taiwan. Work at NCKU was supported by MOST, Taiwan, under grant MOST107-2627-E-006-001 and Higher Education Sprout Project, Ministry of Education to the Headquarters of University Advancement at NCKU. Publisher Copyright: {\textcopyright} 2023, The Author(s).",
year = "2023",
month = dec,
doi = "10.1038/s41467-023-37931-w",
language = "English (US)",
volume = "14",
journal = "Nature communications",
issn = "2041-1723",
publisher = "Nature Publishing Group",
number = "1",
}