Fig. 3: Two-photon coherent backscattering from disorder.
From: Fast multi-source nanophotonic simulations using augmented partial factorization
a, Schematic of the system: maximally entangled photon pairs are reflected from a dynamic disordered medium, and the photon number correlation \({{{\varGamma }}}_{ba}=\langle \psi | :{\hat{n}}_{b}\,{\hat{n}}_{a}:| \psi \rangle\) of the two-photon wave function \(\left\vert \psi \right\rangle\) is measured for pairs of reflected angles θa and θb for which the photon number operators are \({\hat{n}}_{a}\) and \({\hat{n}}_{b}\). This Γba is proportional to the square of the reflection matrix, as shown in equation (4). b,c, Γba for a single realization (b) and \(\overline{{{{\varGamma }}}_{ba}}\) averaged over 4,000 realizations (c), normalized by \(\overline{{{{\varGamma }}}_{ba}}\) away from the coherent backscattering peak.
