# Two-photon superbunching of pseudothermal light in a Hanbury Brown-Twiss interferometer

## TL;DR

This paper demonstrates that adding multiple two-photon paths using rotating ground glasses significantly enhances the degree of photon bunching in pseudothermal light, with potential applications in improving ghost imaging.

## Contribution

It introduces a method to achieve two-photon superbunching in pseudothermal light by adding multiple two-photon paths, with both theoretical and experimental validation.

## Key findings

- Achieved g(2)(0) = 7.10 experimentally with three ground glasses.
- Predicted increase of coherence degree to 32 and 7776 with five ground glasses.
- Enhanced understanding of superbunching physics and ghost imaging visibility.

## Abstract

Two-photon superbunching of pseudothermal light is observed with single-mode continuous-wave laser light in a linear optical system. By adding more two-photon paths via three rotating ground glasses,g(2)(0) = 7.10 is experimentally observed. The second-order temporal coherence function of superbunching pseudothermal light is theoretically and experimentally studied in detail. It is predicted that the degree of coherence of light can be increased dramatically by adding more multi-photon paths. For instance, the degree of the second- and third-order coherence of the superbunching pseudothermal light with five rotating ground glasses can reach 32 and 7776, respectively. The results are helpful to understand the physics of superbunching and to improve the visibility of thermal light ghost imaging.