Researchers demonstrate first terahertz quantum sensing
(PHYSorg.com Physics)

Quantum physicists rely on quantum sensing as a highly attractive method to access spectral regions and detect photons (tiny packets of light) that are generally technically challenging. They can gather sample information in the spectral region of interest and transfer the details via biphoton correlations into another spectral range with highly sensitive detectors. The work is specifically beneficial for terahertz radiation without semiconductor detectors, where physicists must use coherent detection schemes or cryogenically cooled bolometers instead. In a new report on Science Advances, Mirco Kutas and a research team in the departments of industrial mathematics and physics in Germany described the first demonstration of quantum sensing in the terahertz frequency range. During the experiments, terahertz frequencies interacted with a sample in free space and provided information about the sample thickness by detecting the visible photons. The team obtained layer thickness measurements with terahertz photons based on biphoton interference. Since the ability to measure layer thickness non-destructively is of high industrial relevance, Kutas et al. expect these experiments to be a first step toward industrial quantum sensing.