Coherent two-photon backscattering and quantum interference in multiple scattering of entangled and classically correlated light

The classical Coherent Backscattering (CBS) enhancement of light from disordered structures is a recognized manifestation of the weak localization of photons occurring in multiple scattering of light. While this classical effect is well-explored for coherent classical excitations, the natural question of whether and how this effect may arise in the presence of quantum fields is a subject of emerging interest. We present the emergence of coherent two-photon backscattering (CTPBS), an effect analogous to the classical CBS phenomenon, in multiple scattering of two-photon states of the light with quantum and classical correlations. We investigate the effect of multiple relevant parameters in this study including the entanglement dimensionality of the excitation as well as the disorder density on the CTPBS effect and investigate the interplay between the induced and preserved correlations throughout the multiple scattering process. Our study captures the essence of this new effect in connection with coherent and incoherent superpositions and paves the way for exploring this phenomenon as a new diagnostic technique in the realm of quantum physics.