Journal of Physics B Atomic Molecular and Optical Physics
The role of four-photon bunching in fourth-order correlation of thermal light in the photon counting regime
Feng Wen, Xun Zhang, Chenzhi Yuan, Huaibin Zheng, Xin Yao, Zepei Li, Yanpeng Zhang
Abstract
Abstract We theoretically discuss the fourth-order spatial correlation and four-photon bunching properties of pseudo-thermal light in the photon counting regime. It is found that four-photon bunching has the maximum correlation. If they all come from the same spatial cell in phase space, then fourth-order spatial correlation can be decomposed into not only auto-correlation and cross-correlation of second- and third- order, but the pure correlations among four photons as well, which is just the four-photon bunching. In addition, we also show that the contribution from four-photon bunching leads to the enhancement of the resolution and visibility in fourth-order ghost imaging. More precisely, the contribution from four-photon bunching to fourth-order spatial correlation is equal to the sum of all contributions from two-photon bunching and three-photon bunching when three reference detectors are scanned along the identical orientation and speed. On the other hand, the sum of all contributions from two-photon bunching and three-photon bunching to fourth-order spatial correlation will exceed the contribution from four-photon bunching, when two of three reference detectors are scanned in the same orientation and the speed of one reference detector is twice that of the other; meanwhile, the other two reference detectors are moved with opposite orientation but identical speed.