Random phase perturbations in dynamic media fundamentally limit a broad class of conventional optical imaging, causing severe motion artifacts and resolution degradation in applications from in vivo biomedical tomography to remote sensing. Here, we demonstrate that quantum optical coherence tomography (QOCT), leveraging Hong–Ou–Mandel interference of entangled photons, achieves unprecedented resilience against these disturbances and provides quantitative formulas characterizing this robustness. Theoretically, QOCT exhibits >10-fold slower visibility decay than classical optical coherence tomography (OCT) under random phase fluctuations. Experimentally, it maintains >90 % baseline visibility through turbulent media—conditions where OCT fails. Crucially, this robustness stems from intrinsic quantum properties: interference detection between indistinguishable paths of frequency-entangled identical photons eliminates random path length perturbations and provides native axial resolution doubling (versus classical OCT at identical bandwidth), with neither post-processing nor system modifications required. We validate QOCT’s capability by performing micron-scale 3D tomography of structured targets through dynamic turbid liquids, achieving high-fidelity reconstructions under strong flow turbulence (Reynolds number >5600). This work establishes a paradigm for quantum-enhanced imaging, enabling high-precision volumetric tomography in scenarios from motion artifact-free biological diagnosis to non-contact subaquatic mapping through turbulent air–water interfaces.
Random phase perturbations in dynamic media fundamentally limit a broad class of conventional optical imaging, causing severe motion artifacts and resolution degradation in applications from in vivo biomedical tomography to remote sensing. Here, we demonstrate that quantum optical coherence tomography (QOCT), leveraging Hong–Ou–Mandel interference of entangled photons, achieves unprecedented resilience against these disturbances and provides quantitative formulas characterizing this robustness. Theoretically, QOCT exhibits >10-fold slower visibility decay than classical optical coherence tomography (OCT) under random phase fluctuations. Experimentally, it maintains >90 % baseline visibility through turbulent media—conditions where OCT fails. Crucially, this robustness stems from intrinsic quantum properties: interference detection between indistinguishable paths of frequency-entangled identical photons eliminates random path length perturbations and provides native axial resolution doubling (versus classical OCT at identical bandwidth), with neither post-processing nor system modifications required. We validate QOCT’s capability by performing micron-scale 3D tomography of structured targets through dynamic turbid liquids, achieving high-fidelity reconstructions under strong flow turbulence (Reynolds number >5600). This work establishes a paradigm for quantum-enhanced imaging, enabling high-precision volumetric tomography in scenarios from motion artifact-free biological diagnosis to non-contact subaquatic mapping through turbulent air–water interfaces.
Two-photon interference is a cornerstone of quantum optics, enabling imaging, sensing, and precision measurements that surpass classical limits. By harnessing the quantum interference of photon pairs, as demonstrated by the Hong-Ou-Mandel effect, this approach offers superior axial resolution and intrinsic dispersion cancellation, along with strong noise suppression arising from the precise temporal correlations between photons. Building on these principles, we present the theoretical framework and experimental realization of phase-dependent quantum optical coherence tomography (QOCT), a technique that employs phase-modulated two-photon interference for noninvasive morphological analysis of multilayered samples. We demonstrate that introducing controlled phase shifts to photon pairs in a Hong-Ou-Mandel interferometer effectively eliminates artifacts caused by reflections at different sample layers, thereby greatly improving the accuracy and reliability of QOCT measurements. This work advances the fundamental understanding and practical deployment of two-photon interference, overcoming a key limitation in applying QOCT to real-world applications such as biomedical imaging and materials characterization.
Quantum technologies harness the intrinsic nature of quantum physics to beat limitations of classical methods. Recently, the application of quantum entanglement to metrology has attracted much attention. Quantum optical coherence tomography (QOCT) using two-photon interference between entangled photon pairs can overcome certain problems with classical optical coherence tomography (OCT). As the resolution of OCT becomes higher, degradation of the resolution due to dispersion becomes more critical. Here we show our work on the realization of 0.54 μm resolution two-photon interference, which surpasses the current record resolution 0.75 μm for OCT. In addition, the resolution for QOCT showed almost no change even when a 1-mm-thick water was inserted in the path of the interferometer. The results presented here represent a breakthrough for the realization of ultrahigh-resolution quantum metrology. Our work will open up possibilities for medical and biological applications.
Optical coherence tomography (OCT) has been widely used in many applications owing to its non-invasive nature. However, its axial resolution can be degraded due to dispersion in samples and optical systems. Quantum optical coherence tomography (QOCT) can overcome this problem and has thus attracted attention. However, QOCT exhibits two challenges: insufficient volume resolution and artifacts in images. Here, we realize high-volume-resolution QOCT imaging with efficient artifact removal. We evaluate our QOCT system to have an axial resolution of 1.5 μm and a lateral resolution of 1.6 μm, giving a volume resolution of 4.0 μm 3 (4.0 fL). We show that high-volume-resolution QOCT imaging is achievable even under group velocity dispersion. We also show that artifacts appearing inherently in the QOCT images can be removed by fast post-processing using the maximum clique search in graph theory. We believe that this study paves the way for QOCT imaging of three-dimensional fine structures.
Quantum-optical coherence tomography (QOCT) is an optical sectioning modality based on the quantum interference of entangled photon pairs in the well-known Hong-Ou-Mandel interferometer. Despite its promise, the technique is far from being competitive with current classical OCT devices due to the long required acquisition times, derived from the low photon-pair emission rates. In this work, we, on the one hand, demonstrate a quantum optical coherence microscopy technique, based on full-field QOCT, which employs entangled collinear photon pairs in a Linnik interferometer designed to overcome some of the limitations of previous QOCT implementations, and, on the other hand, test it on representative samples, including glass layers with manufactured transverse patterns and metal-coated biological specimens. In our setup, while the idler photon is collected with a multimode fiber, the signal photon is detected by an intensified charge-coupled device camera, leading to full-field transverse reconstruction through a single-axial acquisition sequence. Interestingly, our setup permits concurrent OCT and QOCT trace acquisition, the former with greater counts and the latter with the benefit of quantum-conferred advantages. We hope that our current results will represent a significant step forward towards the actual applicability of QOCT, e.g., in clinical settings.
Quantum optical coherence tomography (QOCT) is the non-classical counterpart of optical coherence tomography (OCT), by which quantum interference of entangled photon pairs is used to show some advantages over classical OCT. Currently, almost all research on the QOCT focuses on the case with two photons and a twofold improvement in axial resolution has been demonstrated. Here, we introduce the multiple reflections strategy into the QOCT scheme, referencing the multi-pass strategy of the sequential scheme in quantum metrology, and provide a theoretical framework for multi-reflection quantum-optical coherence tomography (MQOCT). According to such a scheme, when the incident light interacts with the sample N times, the axial resolution of MQOCT is theoretically enhanced by a factor of N compared to that of QOCT under the same spectral bandwidth while preserving the dispersion cancellation capability of QOCT. Furthermore, we present a classical optical analogy of MQOCT using P -beam correlated multi-mode broadband beams and experimentally validate it. The classical optical analogy of MQOCT theoretically has the same resolution enhancement capability and dispersion cancellation capability as MQOCT while avoiding the fragility issues associated with the quantum light source which is used in MQOCT.
Quantum-optical coherence tomography (QOCT) combines the principles of classical OCT with the correlation properties of entangled photon pairs [Phys. Rev. A 65, 053817 (2002)]. The standard QOCT configuration is based on the Hong-Ou-Mandel interferometer, which uses entangled photons propagating in separate interferometer arms. This noncollinear configuration imposes practical limitations, e.g., misalignment due to drift and low signal-to-noise. Here, we introduce and implement QOCT based on collinear entangled photons. It makes use of a two-photon Michelson interferometer and offers several advantages, such as simplicity, robustness, and adaptability.