Figure 4

The CHER of the biased spin-boson model. We investigate the nonclassical effects of the relative phase \(\varphi\) between the two coupling constants under the balanced condition. In the left (\(\varphi =2\pi /4\)) and middle (\(\varphi =3\pi /4\)) panels, we can see shallow, and stretched, negative wings, which are further enlarged in the insets. As T increases, the CHER broadens, and the negative wing gradually fades away. As \(\varphi\) approaching \(\pi\) (from left, middle, to right panels), it recovers the conventional model, and, consequently, the CHER for \(\varphi =\pi\) is positive. In these plots, we have assumed \(\omega _{\rm {c}}=1\), \(k_{\rm {B}}/\hbar =1\), and increasing T from 0 to 2 (decreasing opacity).