Parameswaran S A, Gopalakrishnan S
Rudolf Peierls Center for Theoretical Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom.
Department of Physics and Astronomy, CUNY College of Staten Island, Staten Island, New York 10314, USA.
Phys Rev Lett. 2020 Dec 4;125(23):237601. doi: 10.1103/PhysRevLett.125.237601.
We study nonlinear response in quantum spin systems near infinite-randomness critical points. Nonlinear dynamical probes, such as two-dimensional (2D) coherent spectroscopy, can diagnose the nearly localized character of excitations in such systems. We present exact results for nonlinear response in the 1D random transverse-field Ising model, from which we extract information about critical behavior that is absent in linear response. Our analysis yields exact scaling forms for the distribution functions of relaxation times that result from realistic channels for dissipation in random magnets. We argue that our results capture the scaling of relaxation times and nonlinear response in generic random quantum magnets in any spatial dimension.
