Nonequilibrium Many-Body Dynamics

Nonlinear response and nonequilibrium dynamics of many-body systems

The nonlinear response of quantum materials contains a wealth of information that is often hidden in the linear regime. Examples include second-harmonic generation (SHG) as a sensitive probe of electronic symmetry and higher-order conductivities that give insight into the quantum geometry and topology of electronic Bloch states in solids. Two-dimensional coherent THz and Raman spectroscopy are two other powerful nonlinear probes of low-energy excitations in quantum materials, which have recently become available in several labs.

Our group performs theoretical research in this direction, both the understand experimental results and to predict new observable phenomena. For example, we have theoretically shown how 2D THz spectroscopy can directly probe fractionalized quasiparticle properties in the Kitaev honeycomb spin liquid and provide evidence for the emergence of localized Majorana excitations trapped by vison pairs. Our group is also interested in post-quench dynamics close to critical points as well as pump-probe spectroscopy of superconductors and their control via nonequilibrium phonons. 

Research Activities

Selected Talks

Nonlinear interrogation of quantum materials: why higher order response tells you more
Talk given at Missouri S&T, Rolla MS, 13 April 2023

Universal post-quench dynamics at a quantum critical point
Talk given at Rutgers University, Piscataway, New Jersey, 10 March 2016

Selected Publications
  • Yihua Qiang, Victor L. Quito, Thaís V. Trevisan, Peter P. Orth
    Probing Majorana wavefunctions in Kitaev honeycomb spin liquids with second-order two-dimensional spectroscopy
    arXiv:2301.11243 (2023)
  • Tianbai Cui, Xu Yang, Chirag Vaswani, Jigang Wang, Rafael M. Fernandes, Peter P. Orth
    Impact of damping on the superconducting gap dynamics induced by intense terahertz pulses
    Phys. Rev. B 100, 054504 (2019)
  • Xu Yang, Chirag Vaswani, Chris Sundahl, Martin Mootz, Pia Gagel, L. Luo, Jong Hoon Kang, Peter P. Orth, Ilias E. Perakis, Chang Beom Eom & Jigang Wang
    Terahertz-light quantum tuning of a metastable emergent phase hidden by superconductivity
    Nature Materials 17, 586 (2018)
  • Michael Schütt, Peter P. Orth, Alex Levchenko, Rafael M. Fernandes
    Controlling competing orders via nonequilibrium acoustic phonons: Emergence of anisotropic effective electronic temperature
    Phys. Rev. B 97, 035135 (2018)
  • Pia Gagel, Peter P. Orth, Jörg Schmalian
    Universal post-quench prethermalization at a quantum critical point
    Phys. Rev. Lett. 113, 220401 (2014)