The role of four-photon bunching in fourth-order correlation of thermal light in the photon counting regime

• Published in: Journal of physics. B, Atomic, molecular, and optical physics Atomic, molecular, and optical physics, 2015-04, Vol.48 (7), p.75401-8
• Main Authors: Wen, Feng, Zhang, Xun, Yuan, Chenzhi, Zheng, Huaibin, Yao, Xin, Li, Zepei, Zhang, Yanpeng
• Format: Article
• Language: English
• Subjects: Autocorrelation; Bunching; Correlation; Counting; Detectors; Ghosts; interference; Orientation; photon statistics and coherence theory; Photons; quantum fluctuations
• ISSN: 0953-4075; 1361-6455
• DOI: 10.1088/0953-4075/48/7/075401

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.