Optimization of photon correlations by frequency filtering

Photon correlations are a cornerstone of quantum optics. Recent works [E. del Valle, New J. Phys. 15, 025019 (2013); A. Gonzalez-Tudela et al., ibid. 15, 033036 (2013);; C. Sanchez Muñoz et al., Phys. Rev. A 90, 052111 (2014) have shown that by keeping track of the frequency of the photons, rich landscapes of correlations are revealed. Stronger correlations are usually found where the system emission is weak. Here, we characterize both the strength and signal of such correlations, through the introduction of the "frequency-resolved Mandel parameter." We study a plethora of nonlinear quantum systems, showing how one can substantially optimize correlations by combining parameters such as pumping, filtering windows and time delayThis work has been funded by ERC Grant POLAFLOW. E.d.V. acknowledges support from IEF project SQUIRREL (623708), and A.G.-T. acknowledges support from the Alexander Von Humboldt Foundation, IEF project NANOQUIS (625955), and the EU integrated project SIQS