Laser confocal imaging technology has become an important analytical tool in biological, biomedical, and materials science research, offering high imaging precision. However, this technology still has some limitations, especially in imaging biological samples (such as living tissues or cells), where the high intensity of the laser may cause irreversible photodamage. It has been proposed that quantum entangled light sources, instead of laser, can be used to avoid this drawback. In this paper, we experimentally demonstrated a quantum confocal imaging technology employing entangled photon sources with high brightness and stability. In the experiment, we obtained the point-by-point scanning imaging of a targeted area, in which a resolution of 3.91 µm is achieved and the signal-to-noise ratio (SNR) degradation is suppressed. We also theoretically analyzed the potential of quantum confocal imaging to improve SNR performance in photodamage-free imaging. Our results could widen the application fields of confocal imaging technology and pave the way for applying the quantum technology in biological imaging.
Laser confocal imaging technology has become an important analytical tool in biological, biomedical, and materials science research, offering high imaging precision. However, this technology still has some limitations, especially in imaging biological samples (such as living tissues or cells), where the high intensity of the laser may cause irreversible photodamage. It has been proposed that quantum entangled light sources, instead of laser, can be used to avoid this drawback. In this paper, we experimentally demonstrated a quantum confocal imaging technology employing entangled photon sources with high brightness and stability. In the experiment, we obtained the point-by-point scanning imaging of a targeted area, in which a resolution of 3.91 µm is achieved and the signal-to-noise ratio (SNR) degradation is suppressed. We also theoretically analyzed the potential of quantum confocal imaging to improve SNR performance in photodamage-free imaging. Our results could widen the application fields of confocal imaging technology and pave the way for applying the quantum technology in biological imaging.
A study published in the international journal Biomedical Optics Express comprehensively demonstrates the potential of quantum imaging techniques using entangled photons to simultaneously achieve minimal invasiveness (non-destructiveness) and extreme precision when observing biological specimens. It argues that illuminating biological specimens with non-classical states of light, such as entangled photon pairs, can physically block uncorrelated classical background noise and exponentially improve the signal-to-noise ratio (SNR). By utilizing quantum correlations and squeezed light states, it transcends the diffraction limit of conventional optical systems, offering unprecedented resolution to visualize delicate biological structures in their natural state. [Quantum Biology Society] Achieving a perfect balance between minimal invasiveness and extreme precision in biological measurements has long been a challenge in the scientific community. Conventional classical optical imaging techniques required intense illumination to obtain high resolution, which inevitably led to cellular damage and ran into the barrier of physical diffraction limits. A recent study published in the international journal Biomedical Optics Express, titled "Application of quantum imaging in biology," comprehensively highlights how quantum imaging technology based on non-classical light breaks through these classical limitations. A joint research team consisting of Hoda Lotfipour, Hassan Sobhani, Mohamad Taghi Dejpasand, and Morteza Sasani Ghamsari from the Photonics and Quantum Technologies Research School at the Nuclear Science and Technology Research Institute (NSTRI) in Tehran, Iran, published this disruptive review study. ■ Quantum Entanglement Perfectly Blocking Noise The researchers focused on the potential of quantum metrology, which introduces non-classical states of light—particularly methods utilizing entangled photon pairs—into biological imaging. When extremely delicate and fragile biological specimens are illuminated with light in entangled quantum states, significant signals can be precisely sorted out through the strong quantum correlations between photons. Through this process, classical background noise that occurs randomly and independently of the entanglement state is physically blocked, ultimately leading to a remarkable, exponential improvement in the system's signal-to-noise ratio (SNR). ■ Extreme Resolution Without Destructive Sampling This innovative, non-invasive quantum microscopy technique opens the path to visualizing living organisms in their natural state without burning or damaging specimens with intense light energy. Furthermore, by actively exploiting quantum correlations and squeezed light states, it easily surpasses the diffraction limits and shot-noise limits of conventional microscopes, making it possible to observe the minute dynamics of intermolecular interactions. This study eloquently demonstrates that quantum imaging technology, which provides unprecedented ultra-high resolution without the risk of destructive sampling, is the core key that will fundamentally shift the paradigm of next-generation biology and precision medicine research. #QuantumImaging #BiologicalImaging #QuantumEntanglement #NonInvasiveImaging #QuantumMicroscopy #PhotonEntanglement #OvercomingNoiseLimits #QuantumBiology #Biophysics #KoreanQuantumBiologySociety https://pmc.ncbi.nlm.nih.gov/articles/PMC12339294/
Quantum imaging is emerging as a transformative approach for biomedical applications, applying nonclassical properties of light, such as entanglement, squeezing, and quantum correlations, to overcome fundamental limits of conventional techniques. These methods promise superior spatial resolution, enhanced signal-to-noise ratios, improved phase sensitivity, and reduced radiation dose, for potentially safer and more precise imaging for delicate biological samples. Here, we present an overview of quantum optical biomedical imaging technologies as well as quantum-inspired imaging methods, including quantum optical coherence tomography, quantum optical microscopy, ghost imaging, multi-parameter quantum imaging, and imaging with quantum-grade cameras. We describe the operating principles, biomedical applications, and unique advantages of each approach, along with the specific challenges for their translation into real-life practice. This review aims to guide future research toward advancing quantum imaging from experimental demonstrations to impactful biomedical tools.
Quantum entanglement serves as an essential resource across various fields, including quantum communication, quantum computing, and quantum precision measurement. Quantum microscope, as one of the significant applications in quantum precision measurement, could bring revolutionary advancements in both signal-to-noise ratio (SNR) and spatial resolution of imaging. Here, we present a quantum microscopy system that relies on a fully fiber-integrated high-performance energy-time entangled light source operating within the near-infrared II (NIR-II) window. Complemented by tailored real-time data acquisition and processing software, we successfully demonstrate the quantum imaging of a standard target, achieving a SNR of 131.51 ± 6.74 and a spatial resolution of 4.75 ± 0.27 µm. Furthermore, we showcase quantum imaging of cancer cells, unveiling the potential of quantum entanglement in biomedical applications. Our fiber-integrated quantum microscope, characterized by high imaging SNR, instantaneous image capture, and analysis capabilities, marks an important step toward the practical application in life sciences.
Correlation imaging based on entangled light sources offers potential benefits over classical single-photon imaging (SPI) in noisy environments, but also faces challenges such as low brightness, long integration times, and difficulty imaging biological organisms. Here, we propose noise-resistant biologically correlated biphoton imaging (CPI) based on a super-bunching light source, addressing the challenge of severe signal-to-noise ratio degradation in conventional SPI schemes. Our CPI, based on a super-bunching light source with high brightness, broadband spectrum (400–1100 nm), and strong quantum correlation (g 2 (0) ∼ 250), delivers high-performance, noise-resistant operation by extracting correlated photon pairs between the reference and signal paths. Experimental results show that under extreme noise conditions (noise-to-signal ratio up to 600), the structural profile in conventional SPI is entirely obscured by noise. In contrast, CPI still clearly resolves the target structure. Quantitative analysis further reveals that, as noise intensity increases, the imaging visibility of CPI can be enhanced by more than two orders of magnitude compared to SPI schemes. This study confirms the exceptional robustness and practical utility of super-bunching light-based correlated imaging in high-noise environments, offering an effective technical approach for high-quality biological observation in complex optical conditions.
Confocal microscopy provides optical sectioning for three-dimensional imaging but conventionally relies on point-by-point scanning and physical pinholes, limiting imaging speed. Here, we demonstrate that confocal sectioning can instead arise directly from quantum measurement, using spatial correlations in entangled biphoton states. Spatially resolved coincidence measurements in a widefield imaging system suppress contributions from out-of-focus planes, producing optical sectioning in parallel across the whole field of view without physical pinholes or mechanical scanning. In addition, this quantum approach obtains an axial response that, as a result of position-momentum entanglement, is 2-times narrower than that of classical confocal imaging. Our work establishes biphoton correlations as a mechanism for improved confocal imaging and enables parallel, pinhole-free optical sectioning without mechanical scanning.
State-of-the-art microscopes use intense lasers that can severely disturb biological processes, function and viability. This introduces hard limits on performance that only quantum photon correlations can overcome. Here we demonstrate this absolute quantum advantage, achieving signal-to-noise beyond the photodamage-free capacity of conventional microscopy. We achieve this in a coherent Raman microscope, which we use to image molecular bonds within a cell with both quantum-enhanced contrast and sub-wavelength resolution. This allows the observation of nanoscale biological structures that would otherwise not be resolved. Coherent Raman microscopes allow highly selective biomolecular finger-printing in unlabelled specimens, but photodamage is a major roadblock for many applications. By showing that this roadblock can be overcome, our work provides a path towards order-of-magnitude improvements in both sensitivity and imaging speed.