Quantum imaging is an advanced method for microscopy or investigating the optical properties of materials or bio-medical inspections with high accuracy, low noise, and extremely low photo-damage. In previous work, we proposed a quantum imaging technique, in which variations in polarization angle due to reflection or transmission at the sample enhance image contrast in the second-order autocorrelation function at zero delay g2(0). However, the image resolution observed was not satisfactory. In this report, to improve the image quality, the parameters such as coincidence window was optimized to distinguish photon statistics effectively due to change in polarization angle and the objective lens was utilized to focus the entangled photon beams. These modifications enabled optical imaging by accurately detecting slight polarization variations in different media. It is suggested that the proposed method enables a superior imaging performance even in the presence of noise and low-power illumination requirement, offering new possibilities for high-quality imaging applications.
Quantum imaging is an advanced method for microscopy or investigating the optical properties of materials or bio-medical inspections with high accuracy, low noise, and extremely low photo-damage. In previous work, we proposed a quantum imaging technique, in which variations in polarization angle due to reflection or transmission at the sample enhance image contrast in the second-order autocorrelation function at zero delay g2(0). However, the image resolution observed was not satisfactory. In this report, to improve the image quality, the parameters such as coincidence window was optimized to distinguish photon statistics effectively due to change in polarization angle and the objective lens was utilized to focus the entangled photon beams. These modifications enabled optical imaging by accurately detecting slight polarization variations in different media. It is suggested that the proposed method enables a superior imaging performance even in the presence of noise and low-power illumination requirement, offering new possibilities for high-quality imaging applications.
Abstract Quantum imaging is an advanced method for microscopy or investigating the optical properties of materials or bio-medical inspections with high accuracy, low noise, and extremely low photo-damage. In previous work, we proposed a quantum imaging technique, in which variations in polarization angle due to reflection or transmission at the sample enhance image contrast in the second-order autocorrelation function at zero delay g 2(0). However, the image resolution observed was not satisfactory. In this report, to improve the image quality, the parameters such as coincidence window was optimized to distinguish photon statistics effectively due to change in polarization angle and the objective lens was utilized to focus the entangled photon beams. These modifications enabled optical imaging by accurately detecting slight polarization variations in different media. Although this method is effective for various samples, it has certain limitations for samples that exhibit polarization disturbances, such as those involving photon scattering. Nevertheless, the proposed approach demonstrates superior imaging performance under noisy conditions and low illumination, offering promising possibilities for high-quality quantum imaging applications.
With the advancement of non-classical light sources such as single-photon and entangled-photon sources, innovative microscopy based on quantum principles has been proposed for traditional microscopy. This paper introduces the experimental demonstration of a quantum polarization microscopic technique that incorporates a quantum-entangled photon source. Although the point that employs the variation in polarization angle due to reflection or transmission at the sample is similar to classical polarization microscopy, the method for constructing the image contrast is significantly different. The image contrast is constructed by the coincidence count of signal and idler photons. In the case that the coincidence count is recorded from both the signal and idler photons, the photon statistics resemble a thermal state, similar to the blackbody radiation, but with a significantly higher peak intensity in the second-order autocorrelation function at zero delay that is derived from the coincidence count, while, when the coincidence count is taken from either the signal or idler photon only, although the photon state exhibits a thermal state again, the photon statistics become more dispersive and result in a lower peak intensity of the autocorrelation function. These different thermal states can be switched by slightly changing the photon polarization, which is suddenly aroused within a narrow range of the analyzer angle. The autocorrelation function g2(0) at the thermal state exhibits a sensitivity that is three times higher compared to the classical coincidence count rate, and this concept can be effectively utilized to enhance the contrast of the image. One of the key achievements of our proposed method is ensuring a low power of illumination (in the order of Pico-joules) for constructing the image. In addition, the robustness without any precise setup is also favorable for practical use. This polarization microscopic technique can provide a superior imaging technique compared to the classical method, opening a new frontier for research in material sciences, biology, and other fields requiring high-resolution imaging.
With the advancement of non-classical light sources such as single-photon and entangled-photon sources, innovative microscopy based on the quantum principles has been proposed over traditional microscopy. This paper introduces the experimental demonstration of a quantum polarization microscopic technique that incorporates a quantum-entangled photon source. Although the point that employs the variation of polarization angle due to reflection or transmission at the sample is similar to classical polarization microscopy, the method for constructing image contrast is significantly different. Image contrast is constructed by the coincidence count of signal and idler photons. In the case that coincidence count is recorded from both the signal and idler photons, the photon statistics resemble a thermal state, similar to the blackbody radiation, but with a significantly higher peak intensity in the second order autocorrelation function at zero delay that is derived from coincidence count. While, when the coincidence count is taken from either the signal or idler photon only, though the photon state exhibits a thermal state again, the photon statistics become more dispersive and result in a lower peak intensity of the autocorrelation function. These different thermal states can be switched by slightly changing the photon polarization, which is suddenly aroused within narrow range of analyzer angle. This polarization microscopic technique can provide a superior imaging technique compared to the classical method, opening a new frontier for research in material sciences, biology, and other fields requiring high-resolution imaging.
We use entangled photons as the light source in a normal microscope. Using this quantum illumination improves both the resolution and noise rejection in the image. The resolution of any classical imaging system is limited by the diffraction created by the finite size of the imaging lens. By using a light source that emits pairs of entangled photons and carefully controlling a camera that is capable of detecting single photons it is possible to observe these photons arriving two-by-two. Applying camera analysis software to log only these two-by-two events one can form an image from the mid-point (bisector) of each of these pair events. The image formed from the sum of all these bisectors has an improved resolution that surpasses the classical limit. Another advantage of using a quantum illumination is that it allows the two-by-two events from entangled photon pairs to be distinguished from background (classical) light and sensor noise. When processed in this way the resulting image is free of camera noise and any background light may be eliminated. The use of a quantum illumination protocol such as that used here results in the elimination of background light and therefore allows the development of the optical equivalent of quantum radar – a quantum enhanced LIDAR scheme. Using quantum illumination, combined with commercially available cameras that are sensitive to single photons creates a new approach to super-resolution and low noise microscopy. Imaging through noise with quantum illumination, T Gregory, P-A Moreau, E Toninelli, and M J Padgett, Science Advances 6, eaay2652 (2020) Resolution-enhanced quantum imaging by centroid estimation of biphotons, E Toninelli, P-A Moreau, T Gregory, A Mihalyi, M Edgar, N Radwell, and M J Padgett, Optica 6, 347-353 (2019)
Quantum imaging techniques offer enhanced resolution, contrast, and precision at ultralow illumination levels compared to traditional imaging approaches. Relying on the unique properties of entangled photon pairs, two of these techniques stand out: the correlation-based quantum imaging technique provides visibility enhancement in imaging of a low-reflectivity object which is subject to excessive noise and losses, while the interaction-free ghost imaging allows for probing the presence of an object with an ultimately low number of photons. Here we propose a quantum imaging scheme that combines the unique advantages of these two approaches. We show that this scheme offers high-contrast imaging of objects with a minimal number of photons that can minimize thermal noise efficiently and create background-free images. We anticipate that this approach can find application in the imaging of photosensitive biological tissues in a noninvasive and harm-free fashion.
Entangled photons enable quantum imaging to surpass classical limits in resolution and noise. To address long-standing challenges in quantum imaging (such as low signal-to-noise, limited resolvable pixels, and difficulty imaging biological samples), we present imaging by coincidence from entanglement (ICE). ICE leverages spatial and polarization entanglement to enhance resolution, support biological imaging, and quantify birefringence properties. Polarization entanglement enables remote, quantitative measurement of both phase retardation and principal axis orientation without changing input polarization. ICE achieves up to 25-fold stray light suppression relative to classical imaging. We further introduce wide-field quantum microscopy by coincidence (QMC) using symmetric, balanced paths to achieve Heisenberg-limited super-resolution, with up to 155-fold suppression of stray light and improved speed and contrast-to-noise ratio. Together, QMC and ICE represent significant advances in quantum bioimaging, offering low-light, high-resolution, and noninvasive imaging capabilities with potential impact in life sciences and remote sensing.