Extended Data Fig. 7: Dressed state picture of the energy levels under CW two-photon resonant excitation.

(a) Energy level diagram of the bare QD states. (b) Dressed energy level diagram and allowed H-polarized transitions in the rotating frame of the excitation laser, ω_L with XX binding energy \({E}_{B}^{XX}\) obtained by analytically diagonalizing Hamiltonian H_4l for constant driving Ω. V-polarized driving does not affect the H-polarized exicton state \(| {D}_{H}\rangle =| X-H\rangle \) with energy \({E}_{{D}_{H}}=(1/2){E}_{B}^{XX}\). The three remaining states consist of the antisymmetric combination of ground and biexciton state \(| {D}_{0}\rangle =(1/\sqrt{2})[| 0\rangle -| XX\rangle ]\), whose energy remains \({E}_{{D}_{0}}=0\), and two states \(| {D}_{\pm }\rangle =(1/{N}_{\pm })[| 0\rangle +(2E\,{/}_{\pm }\hbar \varOmega )+| XX\rangle ]\) with driving dependent energy \({E}_{\pm }=(1/4){E}_{B}^{XX}\pm (1/4)\sqrt{8{\hbar }^{2}{\varOmega }^{2}+{({E}_{B}^{XX})}^{2}}\). N_± are normalization constants. Thus, the driving-induced gap between \(| {D}_{0}\rangle \) and \(| {D}_{-}\rangle \) as well as between \(| {D}_{H}\rangle \) and \(| {D}_{+}\rangle \) is \(\Delta =-\,(1/4){E}_{B}^{XX}+(1/4)\sqrt{8{\hbar }^{2}{\varOmega }^{2}+{({E}_{B}^{XX})}^{2}}\). (c) Calculated spectrum under driving strength of Ω, and showing the location of peaks which are well described the dressed-level picture in (b).