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We investigate the effect of turbulence on quantum ghost imaging. We use entangled photons and demonstrate that for a novel experimental configuration the effect of turbulence can be greatly diminished. By decoupling the entangled photon source from the ghost imaging central image plane, we are able to dramatically increase the ghost image quality. When imaging a test pattern through turbulence, this method increased the imaged pattern visibility from V = 0.14 +/- 0.04 to V = 0.29 +/- 0.04.
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Traditional ghost imaging experiments exploit position correlations between correlated states of light. These correlations occur directly in spontaneous parametric down-conversion (SPDC), and in such a scenario, the two-photon state used for ghost imaging is symmetric. Here we perform ghost imaging using an anti-symmetric state, engineering the two-photon state symmetry by means of Hong-Ou-Mandel interference. We use both symmetric and anti-symmetric states and show that the ghost imaging setup configuration results in object-image rotations depending on the state selected. Further, the object and imaging arms employ spatial light modulators for the all-digital control of the projections, being able to dynamically change the measuring technique and the spatial properties of the states under study. Finally, we provide a detailed theory that explains the reported observations.
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.
In quantum mechanics, entanglement and correlations are not just a mere sporadic curiosity, but rather common phenomena at the basis of an interacting quantum system. In electron microscopy, such concepts have not been extensively explored yet in all their implications; in particular, inelastic scattering can be reanalyzed in terms of correlation between the electron beam and the sample. While classical inelastic scattering simply implies loss of coherence in the electron beam, performing a joint measurement on the electron beam and the sample excitation could restore the coherence and the lost information. Here, we propose to exploit joint measurement in electron microscopy for a surprising and counter-intuitive application of the concept of ghost imaging. Ghost imaging, first proposed in quantum photonics, can be applied partially in electron microscopy by performing joint measurement between the portion of the transmitted electron beam and a photon emitted from the sample reaching a bucket detector. This would permit us to form a one-dimensional virtual image of an object that even has not interacted with the electron beam directly. This technique is extremely promising for low-dose imaging that requires the minimization of radiation exposure for electron-sensitive materials, because the object interacts with other form of waves, e.g., photons/surface plasmon polaritons, and not the electron beam. We demonstrate this concept theoretically for any inelastic electron-sample interaction in which the electron excites a single quantum of a collective mode, such as a photon, plasmon, phonon, magnon, or any optical polariton.
Non-local point-to-point correlations between two photons have been used to produce ghost images without placing the camera towards the object. Here we theoretically demonstrated and analyzed the advantage of non-Gaussian quantum light in improving the image quality of ghost imaging system over traditional Gaussian light source. For any squeezing degree, the signal-to-noise ratio (SNR) of the ghost image can be enhanced by the non-Gaussian operations of photon addition and subtraction on the two-mode squeezed light source. We find striking evidence that using non-Gaussian coherent operations, the SNR can be promoted to a high level even within the extremely weak squeezing regime. The resulting insight provides new experimental recipes of quantum imaging using non-Gaussian light for illumination.
We develop a concept of metasurface-assisted ghost imaging for non-local discrimination between a set of polarization objects. The specially designed metasurfaces are incorporated in the imaging system to perform parallel state transformations in general elliptical bases of quantum-entangled or classically-correlated photons. Then, only four or fewer correlation measurements between multiple metasurface outputs and a simple polarization-insensitive bucket detector after the object can allow for the identification of fully or partially transparent polarization elements and their arbitrary orientation angles. We rigorously establish that entangled photon states offer a fundamental advantage compared to classical correlations for a broad class of objects. The approach can find applications for real-time and low-light imaging across diverse spectral regions in dynamic environments.
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