The circular photogalvanic effect (CPGE) is the photocurrent generated in an optically active material in response to an applied ac electric field, and it changes sign depending on the chirality of the incident circularly polarized light. It is a non-linear dc current as it is second-order in the applied electric field, and for a certain range of low frequencies, takes on a quantized value proportional to the topological charge for a system which is a source of nonzero Berry flux. We show that for a non-interacting double-Weyl node, the CPGE is proportional to two quanta of Berry flux. On examining the effect of short-ranged Hubbard interactions upto first-order corrections, we find that this quantization is destroyed. This implies that unlike the quantum Hall effect in gapped phases or the chiral anomaly in field theories, the quantization of the CPGE in topological semimetals is not protected.

中文翻译：

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相互作用对双外尔半金属手性光电流量化的影响

圆形光电流效应 (CPGE) 是光学活性材料响应于施加的交流电场而产生的光电流，它根据入射圆偏振光的手性改变符号。它是非线性直流电流，因为它在外加电场中是二阶的，并且对于一定范围的低频，呈现与系统的拓扑电荷成正比的量化值，该系统是非零 Berry 通量的来源. 我们表明，对于非相互作用的双外尔节点，CPGE 与 Berry 通量的两个量子成正比。在检查短程哈伯德相互作用对一阶校正的影响时，我们发现这种量化被破坏了。这意味着与间隙相中的量子霍尔效应或场论中的手征异常不同，