Quantum holography exploits quantum correlation in entangled photon pairs to enhance holography. An inherent principle of holography is that each partial hologram can enhance the reconstruction of the entire object, a property that has not yet been explored in the quantum realm. The current fabrication technology for single-photon detectors is limited, making it extremely challenging to manufacture large-area detectors. Since resolution is directly related to the system aperture, achieving a resolution equivalent to that of a large-area detector under the constraint of a limited detection area is a key challenge for realizing high-resolution quantum holography. Here we demonstrate that the spatial correlations of entangled photons can extract crucial additional information from photon wave packets beyond the boundaries of the experimentally recorded region, where the photons have no direct interaction with the object. We validate the approach experimentally and benchmark it against the approach using only the detection area, achieving the advancements with an increase of up to 15 dB in signal-to-noise ratio and up to approximately tenfold improvement in structural similarity. We show the versatility of the approach by demonstrating significantly improved performance across various objects, including quantum holography of complex biological specimens. This work can advance the nascent field of quantum holography and accelerate its application in life sciences and biological systems.
Quantum holography exploits quantum correlation in entangled photon pairs to enhance holography. An inherent principle of holography is that each partial hologram can enhance the reconstruction of the entire object, a property that has not yet been explored in the quantum realm. The current fabrication technology for single-photon detectors is limited, making it extremely challenging to manufacture large-area detectors. Since resolution is directly related to the system aperture, achieving a resolution equivalent to that of a large-area detector under the constraint of a limited detection area is a key challenge for realizing high-resolution quantum holography. Here we demonstrate that the spatial correlations of entangled photons can extract crucial additional information from photon wave packets beyond the boundaries of the experimentally recorded region, where the photons have no direct interaction with the object. We validate the approach experimentally and benchmark it against the approach using only the detection area, achieving the advancements with an increase of up to 15 dB in signal-to-noise ratio and up to approximately tenfold improvement in structural similarity. We show the versatility of the approach by demonstrating significantly improved performance across various objects, including quantum holography of complex biological specimens. This work can advance the nascent field of quantum holography and accelerate its application in life sciences and biological systems.
This study investigates quantum holography, emphasizing its capability to conduct holographic imaging without the requirement for first-order coherence—a limitation of classical physics. By harnessing quantum entanglement, where image data is embedded in the phase correlation of polarization-entangled photon pairs and spread across the transverse spatial dimension, quantum holography enhances imaging performance. This technique not only improves resolution for polarization-sensitive phase objects but also provides resilience against stochastic phase fluctuations and uncontrolled ambient light, offering significant tangible benefits compared to conventional holography. Additionally, its integration with quantum tomography enables precise analysis of multi-dimensional hyper-entangled states, advancing quantum state analysis. Although current challenges remain, such as extended acquisition times due to technological constraints, ongoing advancements in faster, more affordable sensors are expected to address these issues. As a result, quantum holography is poised to have broad applications in biological imaging, sensing, and the exploration of complex high-dimensional quantum states. These developments position quantum holography as a crucial technology in the future of quantum optical communication and information processing, driving innovation and opening new avenues in these fields.
Quantum imaging usually refers to imaging that takes advantage of quantum entanglement to obtain results beyond the classically achievable limits [1]. Various complex experimental setups are used to obtain quantum images, and even more complex experimental setups are used when the goal is to record and retrieve the phase information of the object. Classical holography offers the possibility to record and retrieve phase information from a hologram [2]. However, in low-light conditions, a major challenge is to record images with a high signal-to-noise ratio. Classical schemes [3]–[5], of course, do not aim to demonstrate the quantum properties of the experiments, and quantum schemes [6]–[8] rely on complex preparation of the light beam and do not necessarily provide an advantage for holographic imaging. To date, no simple quantum scheme with quantum advantage has been developed for low-light holographic imaging.
Holography is an essential technique of generating three-dimensional images. Recently, quantum holography with undetected photons (QHUP) has emerged as a groundbreaking method capable of capturing complex amplitude images. Despite its potential, the practical application of QHUP has been limited by susceptibility to phase disturbances, low interference visibility, and limited spatial resolution. Deep learning, recognized for its ability in processing complex data, holds significant promise in addressing these challenges. In this report, we present an ample advancement in QHUP achieved by harnessing the power of deep learning to extract images from single-shot holograms, resulting in vastly reduced noise and distortion, alongside a notable enhancement in spatial resolution. The proposed and demonstrated deep learning QHUP (DL-QHUP) methodology offers a transformative solution by delivering high-speed imaging, improved spatial resolution, and superior noise resilience, making it suitable for diverse applications across an array of research fields stretching from biomedical imaging to remote sensing. DL-QHUP signifies a crucial leap forward in the realm of holography, demonstrating its immense potential to revolutionize imaging capabilities and pave the way for advancements in various scientific disciplines. The integration of DL-QHUP promises to unlock new possibilities in imaging applications, transcending existing limitations and offering unparalleled performance in challenging environments. Supplementary Information: The online version contains supplementary material available at 10.1186/s43074-024-00155-2.
The retrieval of the phase with single-photon states is a fundamentally and technically challenging endeavor. Here we report an experimental realization of hologram recordings with heralded single-photon illumination and continuous observation of photon statistics. Thereby, we demonstrate the basic principle of holography with single-photon states which cannot be described with the classical wave theory. Under conditions with illumination more than 200 times weaker than the noise of the detector, a hologram (interferogram) recorded with a heralded single-photon source revealed an object not visible with nonheralded illumination and slightly higher intensity. The dramatic improvement in retrieval of amplitude and phase information achieved with the heralded single-photon source can be explained by the strong suppression of noise due to the nonclassical temporal correlation between twin photons and the small coincidence time window. The method could be useful for recording and retrieving amplitude and phase information in the presence of strong noise, for covert imaging, and for imaging of photosensitive biological and material samples.
Holography exploits the interference of a light field reflected/transmitted from an object with a reference beam to obtain a reconstruction of the spatial shape of the object. Classical holography techniques have been very successful in diverse areas such as microscopy, manufacturing technology, and basic science. However, detection constraints for wavelengths outside the visible range restrict the applications for imaging and sensing in general. For overcoming these detection limitations, we implement phase-shifting holography with nonclassical states of light, where we exploit quantum interference between two-photon probability amplitudes in a nonlinear interferometer. We demonstrate that it allows retrieving the spatial shape (amplitude and phase) of the photons transmitted/reflected from the object and thus obtaining an image of the object despite those photons are never detected. Moreover, there is no need to use a well-characterized reference beam, since the two-photon scheme already makes use of one of the photons as reference for holography.
We report the experimental observation of quantum holographic imaging of one-dimensional object with entangled photon pairs, generated in a spontaneous parametric down-conversion process. The signal photons play both roles of “object wave” and “reference wave” in holography but are recorded by a point detector providing only encoding information, while the idler photons travel freely and are locally manipulated with spatial resolution. The holographic image is formed by the two-photon correlation measurement, although both the signal and idler beams are incoherent. Three types of quantum holography schemes are analyzed according to the detection regime of the signal photons.