Third-order Ghost Interference With Thermal Light

The experiment named HBT was performed by Hanbury Brown and Twiss inorder to find a new and precise way to measure the angular diameter of star. Themeasure method through the intensity correlation has attracted great attention. Thetwo-photon ghost interference (GI) based on quantum entangled photon pairs fromspontaneous parametric down-conversion (SPDC) was performed by Shih’s group inthe University of Maryland in1995. However, it is so inefficiency that limits itsapplication in many areas for the quantum entanglement source generating. As a kindof common light source, thermal light is regarded as a ideal alternate of quantumentanglement source. Due to correlation function contains a background term, itcaused that the visibility of the second-order correlation of thermal light imaging isfar below entangled light source in thermal optical correlation imaging. Fortunately,studies on the higher-order intensity correlation effects of thermal light show that thevisibility can be significantly improved by increasing the order N. Then, high-ordercorrelation with thermal light have attracted much attention in the field of quantumoptics.A third-order HBT and ghost interference experiment with pseudo-thermal lightsource in the high-intensity limit has been first performed by actually recording theintensities in three optical paths, instead of using one or two detectors to achieve highorder correlation measurement before. It is shown that not only can the visibility bedramatically enhanced compared to the second-order case as previously theoreticallypredicted, but also that the higher visibility is a consequence of the contribution ofthird-order correlation interaction terms, which is equal to the sum of all contributionsfrom second-order correlation experimentally for the first time. Due to the role ofinterference, when the two reference detectors are scanned in opposite directions,negative values for the third-order correlation term of the intensity fluctuations mayappear. Then, it shows equivalence through comparison of the results obtained in one,two and three optical paths by means of one, two and three CCD cameras, Though the visibility and resolution of third-order spatial HBT-type correlation function ofthermal light when scanning the reference detectors in the opposite directions is muchbetter than that when synchronously scanning them, it does not work for the visibilityand resolution enhancement of the thermal higher-order GI, which proved that thenecessary condition for achieving a interference pattern in Nth-order intensitycorrelation measurements is the synchronous detection of the same light field byreference detectors.in experiment. The phenomenon can be completely explained bythe theory of classical statistical optics.