In standard quantum weak measurements, preselection and postselection of quantum states are implemented in the same photon. Here we go beyond this restrictive setting and demonstrate that the preselection and postselection can be performed in two different photons, if the two photons are polarization entangled. The Pancharatnam-Berry phase metasurface is incorporated in the weak measurement system to perform weak coupling between probe wave function and spin observable. By introducing nonlocal weak measurement into the microscopy imaging system, it allows us to remotely switch different microscopy imaging modes of pure-phase objects, including bright-field, differential, and phase reconstruction. Furthermore, we demonstrate that the nonlocal weak-measurement scheme can prevent almost all environmental noise photons from detection and thus achieves a higher image contrast than the standard scheme at a low photon level. Our results provide the possibility to develop a quantum nonlocal weak-measurement microscope for label-free imaging of transparent biological samples.
In standard quantum weak measurements, preselection and postselection of quantum states are implemented in the same photon. Here we go beyond this restrictive setting and demonstrate that the preselection and postselection can be performed in two different photons, if the two photons are polarization entangled. The Pancharatnam-Berry phase metasurface is incorporated in the weak measurement system to perform weak coupling between probe wave function and spin observable. By introducing nonlocal weak measurement into the microscopy imaging system, it allows us to remotely switch different microscopy imaging modes of pure-phase objects, including bright-field, differential, and phase reconstruction. Furthermore, we demonstrate that the nonlocal weak-measurement scheme can prevent almost all environmental noise photons from detection and thus achieves a higher image contrast than the standard scheme at a low photon level. Our results provide the possibility to develop a quantum nonlocal weak-measurement microscope for label-free imaging of transparent biological samples.
Phase contrast microscopy is essential in optical imaging, but traditional systems are bulky and limited by single-phase modulation, hindering visualization of complex specimens.Metasurfaces, with their subwavelength structures, offer compact integration and versatile light field control.Quantum imaging further enhances performance by leveraging nonclassical photon correlations to suppress classical noise, improve contrast, and enable multifunctional processing.Here, we report, a dual-mode bright-dark phase contrast imaging scheme enabled by quantum metasurface synergy.By combining polarization entanglement from quantum light sources with metasurface phase modulation, our method achieves highcontrast, adaptive bright-dark phase contrast imaging of transparent samples with arbitrary phase distributions under low-light conditions.Compared to classical weak light imaging, quantum illumination suppresses environmental noise at equivalent photon flux, improving the contrast from 0.22 to 0.81.Moreover, quantum polarization entanglement enables remote switching to ensure high-contrast imaging in at least one mode, supporting dynamic observation of biological cells with complex phase structures.This capability is especially valuable in scenarios where physical intervention is difficult, such as in miniaturized systems, in vivo platforms, or extreme environments.Overall, the proposed scheme offers an efficient noninvasive solution for biomedical imaging with strong potential in life science applications.
Edge information of images contains a variety of physical properties such as amplitude, phase, polarization, and frequency. These features usually correspond to the changes of the key structure of objects under measured. Therefore, edge imaging is of great significance in computer vision and optical detection. Here, we propose a controllable edge-enhanced imaging system with weak measurement, utilizing a Pancharatnam-Berry phase metasurface to achieve weak coupling between light and object. By setting the proper pre-selection state and post-selection state, high-contrast edge images are successfully obtained in demonstration experiments. Due to the utilization of metasurface, the proposed system significantly simplifies the complexity of traditional optical imaging methods while maintaining weak coupling controllability. Furthermore, by fine-tuning polarization states in measuring, the real and imaginary parts of the weak value can be flexibly adjusted. Therefore, a continuously adjustable observation between the edge-enhanced imaging mode and the complete imaging mode is achieved. This method provides a promising optical solution for multi-scale image detection.
We develop a concept of metasurface-assisted ghost imaging for nonlocal 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. The approach can find applications for real-time and low-light imaging across diverse spectral regions in dynamic environments.
Phase reconstruction plays a pivotal role in biology, medical imaging, and wavefront sensing. However, multiple measurements and adjustments are usually required for conventional schemes, which inevitably reduces the quality of phase imaging. Here, based on multi-channel metasurface and quantum entanglement source, a simple and integrated quantum analog operation system is proposed to realize quantitative phase reconstruction with a high signal-to-noise ratio (SNR) under a low signal photon level. Without additional measurements and adjustments, four differential images necessary for the phase reconstruction are captured simultaneously. The non-local correlation of entangled photon pairs enables to remotely manipulate working modes of the system. Besides, the consistency of entangled photon pairs in time domain makes it possible to achieve a high SNR imaging by trigger detection. The results may potentially empower the application of metasurfaces in optical chip, wave function reconstruction, and label-free biology imaging.
Phase distribution is crucial for obtaining the whole information of phase object in imaging. However, due to the transparency of phase objects, the phase distribution cannot be obtained in traditional bright-field imaging. Here, we propose a phase distribution reconstruction based on the imaginary value of weak measurement, which is achieved by a Pancharatnam–Berry phase metasurface. Moreover, by adjusting the weak value to a real weak value, amplitude reconstruction can also be achieved. Different parts of weak values can be obtained by controlling the preselection and postselection states. The weak interaction is achieved by the metasurface, which is convenient to control the weak coupling and reduce the complexity of the experimental setup at the same time. Furthermore, the edge contour of objects can also be acquired by the weak measurement, and the edge sharpness is related to types of the weak values, which plays an important role in image resolution. Our method paves a way for quantitative phase imaging and unlabeled biological imaging.
Quantum imaging using entangled photon pairs from spontaneous parametric down-conversion (SPDC) provides fundamental advantages over classical phase imaging in the study of transparent object, such as the operation at ultra-low photon flux and high signal-to-noise ratio [1], [2]. Metasurfaces supporting angle-dependent resonances have recently been employed to achieve phase imaging by extracting phase gradients of incident light [3]. These nanoscale metasurfaces indicate significant potential to replace bulky differential interference contrast microscopes, offering an opportunity for integration into ultra-compact biomedical devices. Together with recent development on metasurface-based quantum light source, this opens up the potential for developing a compact quantum phase imaging device, where metasurfaces serve both generation and detection functions.