Infrared (IR) optical range is important for material characterization and sensing. Also, imaging in the IR range yields superior image contrast due to a significant reduction of scattering losses. Thus IR metrology is widely used in petrochemical, pharma, biomedical, homeland security, and other areas.
Even though there are well-developed conventional methods for IR metrology, the remaining challenges are associated with high cost, low efficiency and regulatory requirements for IR light sources and detectors. To mitigate these issues the team is developing new quantum-enabled techniques which allow them to retrieve properties of materials in the IR range from the measurements of visible range photons. The approach is based on the nonlinear interference of frequency correlated photons produced via spontaneous parametric down conversion (SPDC) [1, 2]. Within this process, one of the photons is generated in the visible range, and its correlated counterpart in the IR range is used to probe the properties of the medium. The visibility and phase of the observed fringes depend on the properties of the IR photon, which interacts with the sample. This allows the team to infer the properties of the sample in the IR range from the measurements of visible range photons. In a series of experiments, they demonstrate the IR spectroscopy [1-3], tunable optical coherence tomography (OCT) , and polarimetry . In all these demonstrations the IR properties (absorption spectra, refractive index, 3D images, and polarization) are inferred from the measurements of the interference pattern in the visible range thus making IR measurements more affordable.
 D. Kalashnikov, A. Paterova, S. Kulik, L. Krivitsky, Nature Photonics 10, 98 (2016).
 A. Paterova, S. Lung, D. Kalashnikov, L. Krivitsky, Scientific reports 7, 42608 (2017).
 A. Paterova, H. Yang, Ch. An, D. Kalashnikov, L. Krivitsky, New Journal of Physics 20, 043015 (2018).
 A. Paterova, H. Yang, Ch. An, D. Kalashnikov, L. Krivitsky, Quantum Science & Technology 3, 025008 (2018).
 A. Paterova, H. Yang, C. An, D. Kalashnikov, L. Krivitsky, Opt. Express 27, 2589-2603 (2019).