Saturday, July 27, 2019

Imaging through Noise with Quantum Illumination

ResearchGate, University of Glasgow, UK, paper "Imaging Through Noise With Quantum Illumination" by Thomas Gregory, Paul-Antoine Moreau, Ermes Toninelli, and Miles J. Padgett proposes a detection technique that preferentially select photon-pair events over isolated background events. This is somewhat similar to what SPAD designers do to reject the sunlight, but not exactly the same:

"The contrast of an image can be degraded by the presence of background light and sensor noise. To overcome this degradation, quantum illumination protocols have been theorised (Science 321 (2008), Physics Review Letters 101 (2008)) that exploit the spatial correlations between photon-pairs. Here we demonstrate the first full-field imaging system using quantum illumination, by an enhanced detection protocol. With our current technology we achieve a rejection of background and stray light of order 5 and also report an image contrast improvement up to a factor of 5.5, which is resilient to both environmental noise and transmission losses. The quantum illumination protocol differs from usual quantum schemes in that the advantage is maintained even in the presence of noise and loss. Our approach may enable laboratory-based quantum imaging to be applied to real-world applications where the suppression of background light and noise is important, such as imaging under low-photon flux and quantum LIDAR."

"We have demonstrated a quantum illumination protocol to perform full-field imaging achieving a contrast enhancement through the suppression of both background light and sensor noise. Structure within the thermal background illumination is potentially a-priori unknown and therefore cannot be suppressed with a simple ad-hoc background subtraction. Through resilience to environmental noise and losses, such a quantum illumination protocol should find applications in real-world implementations including quantum microscopy for low light-level imaging, quantum LIDAR imaging applications, and quantum RADAR. Improvements in detector technologies such as SPAD arrays capable of time-tagging events should enable time-of-flight applications to be realised and applied outside of the laboratory through the increased acquisition speed and time resolution that they enable."


  1. I'm not happy with the paper:
    1. Light is always quantized, so illumination is always a "quantum illumination"
    2. How is "Thermal Illumination" defined? SWIR? MWIR? LWIR? One could use a simple IR blocking filter instead to free the bird... ;-)
    3. The comparison in Fig. 5 shows clearly the better contrast of the classically acquired images. The only thing you have to see that is a histogram based stretch on the classical images in the second column...


  2. did you actually read the paper though? When they say quantum illumination it refers to the photon statistics of the light.
    Similarly, thermal illumination means that the statistics of the noise photons are thermal, rather than non-classical. The wavelength of the "cage" light is exactly the same as the wavelength of the "bird"!


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