Nonlinear optical response from quantum kinetic equation

Understand

Motivated by the nonlinear Hall effect observed in topological semimetals, we studied the photocurrent by the quantum kinetic equation.

• We recovered the shift current and injection current discovered by Sipe et al., and the nonlinear Hall current induced by Berry curvature dipole (BCD) proposed by Inti Sodemann and Liang Fu.
• Especially, we further proposed that 3-form tensor can also induce photocurrent, in addition to the Berry curvature and BCD.
• This work will supplement the existing mechanisms for photocurrent.