Asymptotically exact nonlinear responses in interacting many-body systems (virtual)

Siddharth Parameswaran (U Oxford)

Nov 30. 2021, 14:35 — 15:10

Despite its many successes, linear response has its limitations as a probe of correlated quantum matter. Nonlinear response, and specifically multidimensional coherent spectroscopy (MDCS), provides one way to overcome some of these limitations. MDCS, a staple tool in chemistry and atomic physics of few-body systems, probes higher-order multiple-time correlations of a near-equilibrium system. Experimental efforts are underway to extend this to a probe of both clean [1] and disordered [2] many-body systems, but the theoretical toolbox for computing nonlinear response in interacting quantum systems is primitive. In this talk, I will present two classes of problem where (asymptotically) exact calculations of nonlinear response are possible: (i) disordered systems in the asymptotic scaling regime of infinite-randomness fixed points, where MDCS accesses exponents that characterise the critical points and proximate Griffiths phases [3]; and (ii) interacting integrable systems in one dimension, where generalised hydrodynamics can be leveraged into a formalism to compute multipoint correlators that is exact in the Eulerian hydrodynamic limit, revealing distinctions between free and interacting integrable systems and providing recursive expressions for nonlinear Drude weights [4].



[1] J. Lu et al, Phys. Rev. Lett. 118, 207204 (2017).
[2] F. Mahmood et al, Nat. Phys. 17, 627–631 (2021).
[3] S.A. Parameswaran and S. Gopalakrishnan, Phys. Rev. Lett. 125, 237601 (2020).
[4] M. Fava,S. Biswas, S. Gopalakrishnan, R. Vasseur, and S.A. Parameswaran, PNAS 118, e2106945118 (2021).

Further Information
Erwin Schrödinger Institute - virtual
Associated Event:
Topology, Disorder, and Hydrodynamics in Non-equilibrium Quantum Matter (Online Workshop)
Jörg Schmiedmayer (TU Vienna)
Maksym Serbyn (ISTA, Klosterneuburg)
Romain Vasseur (UMass Amherst)