Spectroscopy and imaging in the mid-infrared ($2.5\mu \mathrm{m}\sim \lambda \sim 25\mu \mathrm{m}$) is bedeviled by the presence of a strong 300-K thermal background at room temperature that makes infrared (IR) detectors decades noisier than can be readily achieved in the visible. The technique of imaging with undetected photons (IUP) exploits the quantum correlations between entangled photon pairs to transfer image information from one spectral region to another, and here we show that it does so in a way that is immune to the thermal background. This means that IUP can be used to perform high-speed photon-counting measurements across the mid-IR spectrum, using uncooled visible detectors that are many times cheaper, faster, and more sensitive than their IR counterparts.

• Received 15 March 2023
• Accepted 18 July 2023

DOI:https://doi.org/10.1103/PhysRevA.108.032613

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Published by the American Physical Society