One of the challenges of quantum technologies is realizing the quantum advantage, predicted for ideal systems, in real applications, which have to cope with decoherence and inefficiencies. In quantum metrology, sub-shot-noise quantum imaging (SSNQI) and sensing methods can provide genuine quantum enhancement in realistic situations. However, wide-field SSNQI schemes realized so far suffer a trade-off between the resolution and the sensitivity gain over a classical counterpart: small pixels or integrating area are necessary to achieve high imaging resolution, but larger pixels allow a better detection efficiency of quantum correlations, which means a larger quantum advantage. Here, we show how the SSNQI protocol can be optimized to significantly improve the resolution without giving up the quantum advantage in sensitivity. We show a linear resolution improvement (up to a factor 3) with respect to the simple protocol used in previous demonstrations.
One of the challenges of quantum technologies is realizing the quantum advantage, predicted for ideal systems, in real applications, which have to cope with decoherence and inefficiencies. In quantum metrology, sub-shot-noise quantum imaging (SSNQI) and sensing methods can provide genuine quantum enhancement in realistic situations. However, wide-field SSNQI schemes realized so far suffer a trade-off between the resolution and the sensitivity gain over a classical counterpart: small pixels or integrating area are necessary to achieve high imaging resolution, but larger pixels allow a better detection efficiency of quantum correlations, which means a larger quantum advantage. Here, we show how the SSNQI protocol can be optimized to significantly improve the resolution without giving up the quantum advantage in sensitivity. We show a linear resolution improvement (up to a factor 3) with respect to the simple protocol used in previous demonstrations.
Recently, several proof of principle experiments have demonstrated the advantages of quantum technologies over classical schemes. The present challenge is to surpass the limits of proof of principle demonstrations to approach real applications. This letter presents such an achievement in the field of quantum enhanced imaging. In particular, we describe the realization of a sub-shot-noise wide field microscope based on spatially multi-mode non-classical photon number correlations in twin beams. The microscope produces realtime images of 8000 pixels at full resolution, for a 500 μm2 field of view, with noise reduced to 80% of the shot noise level (for each pixel), which is suitable for absorption imaging of complex structures. By fast post-elaboration, specifically applying a quantum enhanced median filter, the noise can be further reduced (to <30% of the shot noise level) by setting a trade-off with the resolution, thus achieving the best sensitivity per incident photon reported in absorption microscopy. A new microscope instantly captures thousands of photons from faint objects with signal-to-noise ratios exceeding classical limits. Imaging of sensitive objects, such as live cells, limits the optical power that lasers can apply. Now, Alice Meda from Italy's INRIM and colleagues have developed a microscope that ’squeezes‘ light to overcome intensity-limiting shot noise caused by quantum fluctuations of photons. Their sub-shot-noise microscope uses a nonlinear crystal to generate two high correlated light beams impossible for classical waves. Microscale pixels recorded intensities when one beam strikes a sample can have their shot noise reduced by 20% by subtracting correlated patterns from the second reference beam. This quantum-enhanced noise reduction enables the microscope to operate for high sensitive, dynamic, wide field, Q imaging applications.
Summary form only given. In the last years several proof of principle experiments have demonstrated the advantages of quantum technologies respect to classical schemes in imaging, metrology and sensing. The present challenge is to overcome the limits of proof of principle demonstrations to approach real applications. Here, we present the such an achievement in the field of quantum enhanced imaging. In particular, we describe the realization of a sub-shot-noise (SSN) wide field microscope (see Ref. [1]), based on spatially multi-mode non-classical photon number correlations [2]. The microscope produces real-time images of 8000 pixels at full resolution, for (500μm)2field-of-view, with noise reduced at 80% of the shot noise level in each pixel. This is suitable for absorption imaging of complex structures, like biological samples. By simple post-elaboration, specifically applying a “quantum enhanced median filter”, the noise is further reduced (less than 30% of the shot noise level) by setting a trade-off with the resolution. It realizes the best sensitivity per incident photon ever achieved in absorption microscopy.
Recovering both amplitude and phase information from a system is a fundamental goal of optical imaging. At the same time, it is crucial to operate at low photon doses to avoid altering the sample, particularly in biological applications. Quantum imaging provides a powerful route to extract more information per photon than classical techniques, which are ultimately limited by shot-noise. However, the trade-off between quantum noise reduction and spatial resolution has long been regarded as a major obstacle to the application of quantum techniques to small cellular and sub-cellular structures, where they could offer the greatest benefits. Here, we overcome this limitation by demonstrating sub-shot-noise quantitative phase imaging of biological cells based on the transport-of-intensity equation, enabling high-fidelity, label-free imaging of key cellular and sub-cellular features. We achieve high-resolution phase imaging limited only by the numerical aperture, while simultaneously obtaining a resolution-independent quantum advantage. Unlike other quantum imaging approaches, our method operates in a quasi-single-shot, wide-field configuration, retrieves both phase and amplitude information, and does not rely on interferometric measurements, making it intrinsically fast and stable. These results pave the way for the immediate application of sub-shot-noise imaging in biological microscopy.
Sub-Shot Noise quantum imaging is a novel quantum method allowing in principle to recover the image of a weak absorbing object, even if illuminated by a low photon flux, with a signal to noise ratio larger than classical imaging techniques. Here we present the first realization of a genuine quantum imaging schemes exploiting correlation of twin beams produced by Parametric Down conversion. We compare its performances with respect to the corresponding classical scheme, showing a clear improvement of the sensitivity in the reconstruction of the absorbtion profile of a weak object.
Far-field optical imaging inevitably involves low-pass spatial filtering, limiting the resolution. Moreover, conventional imaging suppresses high spatial frequency components close to the cutoff, making them invisible under noise, particularly the shot noise arising from discrete and random nature of quantum light. Here we propose and implement a method for reducing the effect of this noise by optically pre-processing the incoming light prior to detection, thereby optimizing the quantum measurement performed on it. Our scheme, termed Fourier Domain Division (FDD), partitions the Fourier plane into multiple regions for independent detection and subsequent post-processing for image reconstruction. By analyzing the quantum and classical Fisher information, we show that our method is advantageous with respect to direct imaging for high spatial-frequency components. As a result, the number of photons required to achieve a certain signal-to-noise-ratio in the Fourier domain is reduced, thus enhancing the overall resolution in the photon-starved regime. We demonstrate our method in microscopy, achieving 5-fold improvement of Fisher information on high spatial-frequency components. Unlike active super-resolution methods, FDD is passive, making it broadly applicable in microscopy and other imaging scenarios where active illumination is impractical, including astronomy and remote sensing. Our work establishes a general strategy for designing quantum optimized superresolution imaging systems, bridging fundamental quantum limits, practical image analysis and computer vision applications.
Quantum technologies promise to overcome by far the limits of the classical schemes. However, the present challenge is to overpass the limits of proof of principle demonstrations to approach real applications. In this paper, we present an experiment which aims to bridge this gap in the field of quantum enhanced imaging. In particular, we realize a sub-shot noise wide field microscope based on spatially multi-mode non-classical photon number correlations in twin beams. The microscope produces real time images of 8000 pixels at full resolution, with noise reduced to the 80% of the shot noise level (for each pixel), hence able to image faint samples at low illumination level. The noise can be further reduced (less than 30% of the shot noise level) turning down the resolution. It demonstrates the best sensitivity per incident photon ever achieved in absorption microscopy.