Anti-bunching in two-photon correlations from a doubly driven Raman source is shown to have spatial periodicity comparable to optical two-slit interference. This can be applied to enhance microscopic resolution.
Spatial anti-bunching, in contrast to the well-known bunching behavior observed in classical light sources, describes a situation where photons tend to avoid each other in space, resulting in a reduced probability of detecting two or more photons in proximity. This anti-bunching effect, a hallmark of nonclassical light, signifies a deviation from classical intensity fluctuations and has been observed not only in free electrons and entangled photon pairs but also in chaotic-thermal light. This work investigates the generation mechanism of spatial anti-bunching correlation in random light fields, leveraging the wandering of light centers to induce a second-order coherence degree below unity. Unlike traditional Gaussian Schell-model partially coherent light, this work predicts the emergence of two fundamentally distinct orbital angular momentum states, arising from the inherent differences between rigid body rotation and fluid-like rotation in the wandering light. These predictions are supported by experimental evidence. Based on these findings, we propose a resolution-enhanced lensless ghost imaging system as an application example. Experimental results indicate that the adoption of the anti-bunching correlated light field as the illumination source enables the imaging system to attain super-resolution imaging capabilities. Our findings provide new insights into the utilization of anti-correlated light fields for precision imaging and detection applications.
A recently introduced two-channel confocal microscope with correlated detection promises up to 50% improvement in transverse spatial resolution [Simon, Sergienko, Optics Express 18, 9765 (2010)] via the use of photon correlations. Here we achieve similar results in a different manner, introducing a triple-confocal correlated microscope which exploits the correlations present in optical parametric amplifiers. It is based on tight focusing of pump radiation onto a thin sample positioned in front of a nonlinear crystal, followed by coincidence detection of signal and idler photons, each focused onto a pinhole. This approach offers further resolution enhancement in confocal microscopy.
Quantum correlation of two-photon states has been utilized to suppress the environmental noise in imaging down to the single-photon level. However, the size of the coherence area of photon pairs limits the applications of quantum imaging based on spatial correlations. Here, we propose a quantum imaging scheme exploiting twisted photon pairs with tunable spatial-correlation regions to circumvent this limitation. We employ a bulk-density coincidence to enhance the imaging signal. Specifically, we introduce a re-scaled image signal, which is immune to the background intensity distribution profile of the photon pulse. We reveal a destructive interference between the anti-bunched photon pair and bunched photon pair in the imaging process. Our work could pave a way for twisted-photon-based quantum holography and quantum microscopy.