Three-body correlations in nonlinear response of correlated quantum liquid

Behavior of quantum liquids is a fascinating topic in physics. Even in a strongly correlated case, the linear response of a given system to an external field is described by the fluctuation-dissipation relations based on the two-body correlations in the equilibrium. However, to explore nonlinear non-equilibrium behaviors of the system beyond this well-established regime, the role of higher order correlations starting from the three-body correlations must be revealed. In this work, we experimentally investigate a controllable quantum liquid realized in a Kondo-correlated quantum dot and prove the relevance of the three-body correlations in the nonlinear conductance at finite magnetic field, which validates the recent Fermi liquid theory extended to the non-equilibrium regime.

Optimal solid state neurons

Bioelectronic medicine is driving the need for neuromorphic microcircuits that integrate raw nervous stimuli and respond identically to biological neurons. However, designing such circuits remains a challenge. Here we estimate the parameters of highly nonlinear conductance models and derive the ab initio equations of intracellular currents and membrane voltages embodied in analog solid-state electronics. By configuring individual ion channels of solid-state neurons with parameters estimated from large-scale assimilation of electrophysiological recordings, we successfully transfer the complete dynamics of hippocampal and respiratory neurons in silico. The solid-state neurons are found to respond nearly identically to biological neurons under stimulation by a wide range of current injection protocols. The optimization of nonlinear models demonstrates a powerful method for programming analog electronic circuits. This approach offers a route for repairing diseased biocircuits and emulating their function with biomedical implants that can adapt to biofeedback.

Модифицированная модель Друде-Лоренца, позволяющая учесть топологические характеристики среды

The Drude-Lorentz model, which allows to describe nonlinear response of dielectric or conduc-tor, could be used for describing nonlinear non resonant responses of some exotic media, such as the topological insulators, the Weyl semimetals and the Dirac metals. Generalized Drude-Lorentz model and its simplified version, where the topological effects are taken into account in the minimal order, are presented in paper. A nonlinear conductance of the second order corre-sponding to second harmonic generation and optical rectification effect is obtained in paper as an example of use of the simplified model. It is shown that the ratio of the topological conductance to the ordinary linear conductance contains the constant value that is proportional to the fine structure constant and axion field gradient.