Fig. 5: Pump-2DTS probe spectroscopy of a hypothetical non-equilibrium phase transition.
From: Multidimensional terahertz probes of quantum materials
Evolution of the nonlinear optical response is shown as a function of pump-2DTS probe delay tp−p. Before arrival of the pump pulse (tp−p < 0), the system is unordered at thermal equilibrium and no rephasing nonlinearity is observed at the salient collective mode frequency ω0. Upon arrival of the pump pulse Epump (tp−p = 0), a non-equilibrium phase transition is initiated. At short timescales (tp−p > 0) the non-equilibrium phase is disordered, reflected by an elongated peak in the rephasing 2-D spectrum. At long timescales (tp−p ≫ 0), the disorder resolves and the rephasing 2-D spectrum becomes correspondingly symmetric.
