Quantum imaging utilizes the correlation of photons to enhance the security, covertness, and noise resilience of optical imaging. Despite recent advances, developing a quantum imaging system with long-distance and strong noise resilience remains challenging. Here, we present an experimental demonstration of high-performance quantum imaging at telecom band with enhanced noise resilience. We use a fiber-integrated quantum light source via cascaded second-order nonlinear processes to generate high-quality correlated/entangled photon pairs at telecom band and a fiber-coupled confocal optical system to effectively suppress the background noise and improve the collection efficiency of echo signal photons by optimizing its bandwidth and aperture. In our demonstration, the quantum imaging with correlated/entangled photon pairs or heralded single photons is achieved at a distance of 11 m under indoor illumination. When the detected environment noise is 33 dB stronger than the signal photons, corresponding to a coincidence-to-accidental coincidence ratio of 1.7 ± 0.1, an imaging contrast of 0.23 ± 0.09 is achieved, which is 46 times higher than single-photon imaging without correlation. The results will open venues for the development of practical quantum imaging techniques.
Quantum imaging utilizes the correlation of photons to enhance the security, covertness, and noise resilience of optical imaging. Despite recent advances, developing a quantum imaging system with long-distance and strong noise resilience remains challenging. Here, we present an experimental demonstration of high-performance quantum imaging at telecom band with enhanced noise resilience. We use a fiber-integrated quantum light source via cascaded second-order nonlinear processes to generate high-quality correlated/entangled photon pairs at telecom band and a fiber-coupled confocal optical system to effectively suppress the background noise and improve the collection efficiency of echo signal photons by optimizing its bandwidth and aperture. In our demonstration, the quantum imaging with correlated/entangled photon pairs or heralded single photons is achieved at a distance of 11 m under indoor illumination. When the detected environment noise is 33 dB stronger than the signal photons, corresponding to a coincidence-to-accidental coincidence ratio of 1.7 ± 0.1, an imaging contrast of 0.23 ± 0.09 is achieved, which is 46 times higher than single-photon imaging without correlation. The results will open venues for the development of practical quantum imaging techniques.
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.
Quantum imaging utilizing entangled photon pairs takes advantage of their strong quantum correlations to surpass the limitations of classical imaging techniques in terms of spatial resolution and signal-to-noise ratio. However, due to the low brightness of entangled photon sources, an enormous number of intensity images (∼107) is required for imaging in previous studies in order to acquire images with a sufficient signal-to-noise ratio, posing a challenge for practical implementation. A BiBO crystal, known for its large nonlinear optical coefficient, is considered a promising high-brightness entangled photon source. However, its performance has not been quantitatively evaluated in the context of quantum imaging systems, particularly regarding its impact on imaging performance. Here, we investigate the potential of a BiBO crystal as a light source for high-efficiency quantum imaging by performing parallel intensity correlation measurements and implementing quantum image distillation as an example in comparison with a commonly used BBO crystal. The results demonstrate that the use of the BiBO crystal enables more efficient quantum imaging compared to the conventional BBO crystal.
Single photon–level imaging at 1550 nanometers is a key driver for crucial advancements in the next-generation laser detection technology. This cutting-edge approach plays a vital role in space ranging, target recognition, and three-dimensional remote sensing. However, it has faced severe challenges such as insufficient noise-tolerant performance. Here, we introduced noise-tolerant correlated coincidence imaging (CCI) based on supercorrelated light (SCL). The light source, generated through nonlinear interaction between a pulsed laser and a photonic crystal fiber, exhibits a broader power-law photon number probability distribution and extremely strong photon correlation [with second-order correlation function g (2) (0) up to 18,166]. Our noise-tolerant CCI can resist random environmental noise up to 100,000 times stronger than the echo signal photons. SCL offers an exceptionally strong noise tolerance for single photon–level imaging in extreme environments with intense noise, paving the way for the future development of extremely sensitive light detection.
A high-quality narrowband polarization-entangled source in the telecom band is preferred to avoid frequency dispersion for long-distance transmission in optical fibers and to efficiently couple with telecom-band quantum memories. Here, we report narrowband, telecom-band, polarization-entangled photon pair generation based on the superposition of single-longitudinal-mode photon pairs from two monolithic nonlinear crystal cavities in a passively stable interferometer based on beam displacers. The photon pairs generated from the cavities exhibit a high coincidence to accidental coincidence ratio of 20 000 and a bandwidth below 500 MHz. Two-photon polarization interference, Bell inequality, and quantum state tomography are performed to indicate the high quality of the entangled source. The current configuration demonstrates greater stability than traditional free space cavity-enhanced polarization-entangled state generation, which is promising for quantum communication applications.
Quantum correlations, especially time correlations, are crucial in ghost imaging for significantly reducing the background noise on the one hand while increasing the imaging resolution. Moreover, the time correlations serve as a critical reference, distinguishing between signal and noise, which in turn enable clear visualization of biological samples. Quantum imaging also addresses the challenge involved in imaging delicate biological structures with minimal photon exposure and sample damage. Here, we explore the recent progress in quantum correlation-based imaging, notably its impact on secure imaging and remote sensing protocols as well as on biological imaging. We also exploit the quantum characteristics of heralded single-photon sources (HSPS) combined with decoy state methods for secure imaging. This method uses Quantum Key Distribution (QKD) principles to reduce measurement uncertainties and protect data integrity. It is highly effective in low-photon number regimes for producing high-quality, noise-reduced images. The versatility of decoy state methods with WCSs (WCS) is also discussed, highlighting their suitability for scenarios requiring higher photon numbers. We emphasize the dual advantages of these techniques: improving image quality through noise reduction and enhancing data security with quantum encryption, suggesting significant potential for quantum imaging in various applications, from delicate biological imaging to secure quantum imaging and communication.
Quantum imaging utilizing entangled photon pairs takes advantage of their strong quantum correlations to surpass the limitations of classical imaging techniques in terms of spatial resolution and signal-to-noise ratio. However, due to the low brightness of entangled photon sources, an enormous amount number of intensity images (∼107) is required for imaging, posing a challenge for practical implementation. In this study, we propose the use of a BiBO crystal for generating entangled photons to enhance the efficiency of quantum imaging. A BiBO crystal has large nonlinear optical coefficient, so it has been expected to serve as a high-brightness entangled photon source. However, a BiBO crystal has never been applied to quantum imaging because it's relatively recently discovered. Here, we investigate the potential of a BiBO crystal as a light source for high-efficiency quantum imaging by performing parallel intensity correlation measurements and implementing quantum image distillation as an example in comparison with the commonly used a BBO crystal. As a result, we achieved a tenfold reduction in measurement time of the conventional method and a significant improvement in imaging efficiency.