Quantum Imaging Techniques and Applications

Quantum imaging exploits non-classical properties of light—most notably entanglement and squeezing—to achieve performance beyond the limits of conventional optics. By harnessing correlations between photon pairs or higher-order quantum states, techniques such as ghost imaging, quantum optical coherence tomography and quantum holography offer enhanced resolution, sensitivity and noise resilience. Approaches based on spontaneous parametric downconversion yield entangled biphotons that enable sub-shot-noise measurements and Heisenberg-limited resolution, while quantum illumination protocols maintain imaging advantages even in the presence of loss and background noise. The field has matured to encompass a variety of operational modes, including wide-field and point-scanning microscopy, low-dose X-ray imaging, and remote sensing applications (for example quantum LIDAR). Across biological, materials and security domains, quantum imaging promises lower photon exposure, improved contrast-to-noise ratios and new modalities of information extraction that are inaccessible to classical systems.

Research from Nature Portfolio

Recent studies have demonstrated quantum microscopy by coincidence, in which entangled photon pairs traverse balanced optical paths to behave as effective half-wavelength probes. This configuration achieves a two-fold resolution enhancement at the Heisenberg limit and offers up to 155-fold rejection of stray light, opening pathways to nondestructive bioimaging of live cells with greatly improved speed and contrast. Foundational work on direct absorption measurement has established an absolute per-photon advantage over ideal classical probes: correlated intensity detection of spontaneous parametric downconversion pairs reduces photon doses by around 32 % while maintaining precision beyond the shot-noise limit. Complementary efforts with twin-beam states have shown that quantum-correlated reference beams can self-compensate for source and detector instabilities, attaining ultimate sensitivity in loss estimation across all energy regimes, including sub-single-photon levels.

Research from all publishers

Innovations in non-interferometric quantitative phase imaging exploit entanglement to extend transport-of-intensity methods, delivering wide-field phase retrieval with improved detail discrimination at a fixed photon budget and promising applications from visible to X-ray regimes. An alternative phase-imaging strategy leverages quantum interference between successive downconversion events, achieving nearly twice the phase shift and ~1.7× spatial resolution of equivalent coherent techniques, while operating orders of magnitude faster than conventional coincidence counting—ideal for photosensitive biological specimens. Meanwhile, the integration of machine intelligence with quantum ghost imaging is accelerating image reconstruction and artefact suppression. By combining data-driven algorithms with non-local photon correlations, these hybrid protocols are set to enhance throughput and image fidelity in complex environments.

Quantum Imaging Techniques and Applications publication trend

The graph below shows the total number of articles in quantum imaging techniques and applications across all publications each year (not limited to Nature Index journals).

Technical terms

Entangled photons: Pairs of photons whose quantum states are interdependent, enabling non-classical correlations in measurements.

Squeezing: Reduction of quantum noise in one field quadrature below the shot-noise limit at the expense of increased noise in the conjugate quadrature.

Heisenberg limit: Ultimate bound on measurement precision set by quantum mechanics, scaling inversely with the total number of resources (e.g. photons).

Quantum illumination: Imaging protocol that retains quantum advantage even under high loss and background noise by exploiting initial entanglement.

Ghost imaging: Technique in which an image is reconstructed from correlations between two light fields, only one of which interacts with the object.

Spontaneous parametric downconversion (SPDC): Nonlinear optical process that generates entangled photon pairs from a higher-energy pump photon.

Coincidence counting: Detection method registering simultaneous photon events to isolate correlated pairs from background signals.

References

1. Quantum enhanced non-interferometric quantitative phase imaging. Light: Science & Applications (2023).
2. Quantum microscopy of cells at the Heisenberg limit. Nature Communications (2023).
3. Advances in Quantum Imaging with Machine Intelligence. Laser & Photonics Review (2024).
4. Quantum-enhanced phase imaging without coincidence counting. Optica (2023).
5. Imaging through noise with quantum illumination. Science Advances (2020).
6. Demonstrating an absolute quantum advantage in direct absorption measurement. Scientific Reports (2017).
7. Unbiased estimation of an optical loss at the ultimate quantum limit with twin-beams. Scientific Reports (2018).