Near infrared quantum ghost spectroscopy for threats detection

Quantum sensing is a rapidly growing branch of research within the area of quantum science and technology offering key resources, beyond classical ones, with potential for commercialization of novel (quantum) sensors. The exploitation of quantum resources offered by photons can boost the performance of quantum sensors for innovative and challenging applications. In this paper, we build on the idea that quantum ghost spectroscopy (QGS), i.e. the counterpart in the frequency domain of quantum ghost imaging (QGI), can target specific applications in the detection of possible threats. This is implemented by exploiting the opportunities offered by quantum optics, i.e. the generation of photon pairs characterized by spectral correlations. We will discuss our main results obtained with pure QGS experiments showing that it is possible to assess the presence of a target dealing with a low resources measurement. The time-frequency domain reveals a huge potential for several applications, and frequency correlations represent a versatile tool that can be exploited to enable the spectral analysis of objects where a direct measurement would not be feasible (e.g. due to security). The use of non-degenerate sources of correlated photons allowed to reveal spectral features in the near-infrared wavelengths employing the usual detectors for the visible region, showing the effectiveness of this technique.