Photonic cross-noise spectroscopy of Majorana bound states

We propose a route to detect Majorana bound states (MBSs) by coupling a topological superconductor to quantum dots (QDs) in a pnp junction. Here, two MBSs are coherently coupled to electrons on two QDs, which recombine with holes to photons. We focus on the spectroscopy of cross-correlated shot noise and the polarization of the emitted photons. Our detection scheme allows us to probe the necessary condition for the emergence of MBSs, specifically, the existence of nonlocal triplet superconducting correlations and also the fundamental property that two MBSs comprise a single complex fermion. We compare our results to the ones obtained from nontopological quasi-MBSs (qMBSs) and establish a correspondence between the number of peaks in the cross-correlation with the number of MBSs in the system. Here, we can identify a tunneling regime that facilitates differentiation between topological MBSs and trivial qMBSs. Additionally, we test the robustness of the detection scheme by the addition of uncorrelated quasiparticles.