Photon-statistics-based classical ghost imaging with one single detector

Photon-counting statistics-based support vector machine with multi-mode photon illumination for quantum imaging

We propose a photon-counting-statistics-based imaging process for quantum imaging where background photon noise can be distinguished and eliminated by photon mode estimation from the multi-mode Bose–Einstein distribution. Photon-counting statistics show multi-mode behavior in a practical, low-cost single-photon-level quantum imaging system with a short coherence time and a long measurement time interval. Different mode numbers in photon-counting probability distributions from single-photon illumination and background photon noise can be classified by a machine learning technique such as a support vector machine (SVM). The proposed photon-counting statistics-based support vector machine (PSSVM) learns the difference in the photon-counting distribution of each pixel to distinguish between photons from the source and the background photon noise to improve the image quality. We demonstrated quantum imaging of a binary-image object with photon illumination from a spontaneous parametric down-conversion (SPDC) source. The experiment results show that the PSSVM applied quantum image improves a peak signal-to-noise ratio (PSNR) gain of 2.89dB and a structural similarity index measure (SSIM) gain of 27.7% compared to the conventional direct single-photon imaging.

Ghost Spectroscopy with Classical Correlated Amplified Spontaneous Emission Photons Emitted by An Erbium-Doped Fiber Amplifier

We demonstrate wavelength-wavelength correlations of classical broad-band amplified spontaneous emission (ASE) photons emitted by an erbium-doped fiber amplifier (EDFA) in a wavelength regime around 1530 nm. We then apply these classical correlated photons in the framework of a real-world ghost spectroscopy experiment at a wavelength of 1533 nm to acetylene ( C 2 H 2 ) reproducing the characteristic absorption features of the C-H stretch and rotational bands. This proof-of-principle experiment confirms the generalization of an ASE source concept offering an attractive light source for classical ghost spectroscopy. It is expected that this will enable further disseminating ghost modality schemes by exploiting classical correlated photons towards applications in chemistry, physics and engineering.

Recovering a hidden polarization by ghost polarimetry

By exploiting polarization correlations of light from a broadband fiber-based amplified spontaneous emission source we succeed in reconstructing a hidden polarization in a ghost polarimetry experiment in close analogy to ghost imaging and ghost spectroscopy. Thereby, an original linear polarization state in the object arm of a Mach-Zehnder interferometer configuration which has been camouflaged by a subsequent depolarizer is recovered by correlating it with light from a reference beam. The variation of a linear polarizer placed inside the reference beam results in a Malus law type second-order intensity correlation with high contrast, thus measuring a ghost polarigram.

Characteristic properties of the spatial correlations and visibility in mixed light ghost imaging

Recently, we developed a new ghost imaging (GI) detection concept based on the superposition of object and reference beams with subsequent photon statistics evaluation by using one single photon counting detector (PS-GI). Here, we derive analytical expressions for the spatial correlations of this mixed light GI concept considering the mode properties of the speckles of an illuminating classical pseudothermal source. This model supports the first experimental results of PS-GI in [Opt. Lett.41, 2863-2866 (2016)OPLEDP0146-959210.1364/OL.41.002863] and explains deviating characteristic features in comparison to state-of-the-art GI detection, such as maximum and minimum ghost image signals as well as the visibility performance. Furthermore, the model also explains the higher order correlations, which have been experimentally obtained by using a single detector. The overall good agreement between theory and experiment provides physical insight into the functional principle of mixed light GI, thus fostering PS-GI as a real alternative to established GI technologies.