Quantum imaging leverages quantum correlations to introduce entirely novel imaging techniques, e.g., interaction-free imaging, non-line-of-sight telescope, multidimensional imaging; and to enhance existing imaging technology to attain resolutions beyond classical limits across a range of wavelengths, timescales, and length-scales, e.g., sub-shot-noise imaging, quantum lithography, quantum microscopy. The images produced are not only useful for medicine, military defense, and data storage for secure encrypted information, but also do the cutting-edge technologies related quickly claim forefront translation to industry.

Medical Applications

Quantum Microscope

Light microscopes are indispensable to biotechnology and medicine. Limited by shot noise, better contrast increases with light intensity and brighter light could easily destroy biological specimens. Quantum microscopes taking advantage of entangled photons, sensitive photodetectors and machine learning offer gentler probe that can image classically concealed biological structure. A short list of applications ranges from studying the organization, and interaction of molecular building blocks, and their functional integration into cells, exploring living cells and tissues, optogenetic control of neural networks. Our R&D program for clinical benefits focuses on global medical diagnostic market.

Quantum Tech: Quantum entanglement is a particular correlation that the identity is indivisible even when considerably spatially separated. A high-brightness entangled-photon beam achievable by concentrating light into ultra-short laser pulses statistically compels transmitted photons to arrive at a detector in a very orderly fashion. By doing so, the noise level is largely suppressed and an image with unparallel contrast starts to build up.

Direct Societal Impact: Improved resolution, spectral coverage, and noise rejection of light microscopes.

Collateral Advantages: Ramifications in global positioning, radar, and navigation, quantum ellipsometry,

Alternative Quantum Technology: Photoionization microscopy, light-sheet techniques, super-resolution imaging methods, high-speed microscopes,

Aided System: High brightness entangled photon source.

Computer graphic generated image showing entangle photon pairs passing through a 2D biological specimen. Ref: Nature volume 594, pages201–206 (2021).

Defense and Security Applications

Quantum Radar / Lidar

The keys to development of the next generation radar are 1) more sensitivity to distinguish the signal from the background noises where weak signal from stealth object is noise-alike and 2) difficult-to-detect radar to avoid intentionally signal jamming. Because quantum radar can detect light at single photon level, it is harder to spot by the enemy. With an addition of quantum illumination that relies on streams of entangled photons, building a quiet radar with extremely sensitivity to un-stealth aircrafts / vehicles is on our palms.

Quantum Tech: Through quantum illumination process, a signal photon entangled with an idler photon retained at the base station interrogates a target region that is fully submerged in a noisy background. Both photons are combined, and a joint measurement** based on time-correlation using coincidence counting is performed to determine whether it is in fact the returning photon reflected at the target or just ambient background noise. The required high-brightness and high-efficiency chip-based entangled-photon source* had been made available and are ready for scaling up.

*Tens of millions of entangled photon pairs per second from a single microwatt-powered laser beam (Phys. Rev. Lett. 125, 263602 (2020).

**A joint quantum measurement (JQM) refers to performing one measurement on a single particle to simultaneously deduce two observables which can be complementary defined by pairwise non-commuting operators. There must exist a joint probability distribution that increase variance of the marginal probability distributions to be greater than when the observables were measured alone. Since the requirement to satisfy Bell inequalities and the existence of a joint probability distribution are equivalent, JQM is also used to describe a composite system that represent one identity such as entangled photon pair which is the case discussed here.

Direct Societal Impact: Un-stealth aircrafts / vehicles in noisy atmosphere.

Collateral Advantages: Driving logic gates for quantum computing, communication components, integration into mainstream electronic devices, quantum optical coherence tomography (Hong–Ou–Mandel interferometer).

Alternative Quantum Technology:

Aided System: High brightness and efficiency entangled photon source.

MIT demonstration of quantum illumination at optical frequencies, realizing a 20% increase in signal to noise. Ref: https://www.sciencemag.org/news/2020/09/short-weird-life-and-potential-afterlife-quantum-radar

Quantum Periscope

In classical imaging, the only light entering a camera is directly reflected by all objects in the field of view. However, in some situation, e.g., autonomous vehicles, enemy combatant defense, spying robot, and search-and-rescue missions, non-line-of-sight imaging is considerably crucial. By using single-photon, spatial and temporal measurement (LIDAR) combined with structured illumination, seeing the ‘echoes of light’ is practicable. A highly sensitive detectors using single-photon quantum sensor operating at a trillion frames per second can capture photons bounce back from an object concealed from the direct line-of-sight a hundred meters away. That is the ability to see behind walls, see around corners.

Quantum Tech: By structurally illuminating laser pulses at a wall, i.e., either raster scanning the laser across the scene or used moving microscopic mirror arrays to scan the detector’s field of view over the surface of the reflecting wall, light strikes the wall and fractionally bounces around a barrier toward the hidden object. Only tiny proportion of photons makes a comeback to the detector. The time-of-flight measurement of the returning photons gives the position of the hidden object of which the reconstruction algorithms produce a 3D image in just 0.8 seconds.

Direct Societal Impact: Self-driving vehicles, autonomous robots, enemy combatant defense, spying applications, robotic vision, medical imaging, astronomy (probing the inner structure of lava tubes from orbiting satellites), space exploration, search-and-rescue missions, reading a closed book / concealed file binder.

Collateral Advantages:

Alternative Quantum Technology: Light cone transform with a SPAD camera.

Aided System: High-quantum-efficiency single-photon detector.

(left) Illustrated first seeing behind the wall. (right) seeing around corners grants great advantage in both urban and rural conventional warfare. Ref: https://www.quantamagazine.org/the-new-science-of-seeing-around-corners-20180830/