The microscope was created over 350 years ago and was considered a pioneering discovery at the time. Today, it is an essential tool in many fields of science: chemists, biologists, clinicians, physicists, and even engineers use it to discover the internal structures of organisms and matter that we cannot see with the naked eye. Most of these microscopes use light as the primary tool to illuminate transparent or semi-transparent samples and see what happens inside. However, some delicate samples such as certain molecules and cells can be damaged or even die under intense light radiation, posing problems when conducting high-precision experiments.
To mitigate this problem, the ideal solution is to reduce the intensity of the light, but in doing so, the image tends to become noisy and blurry, obscuring important details that could provide crucial information to the observer. In an effort to overcome this barrier, techniques have been developed to obtain images of very small and sensitive samples without damaging them. One promising option is the use of quantum light.
Since 2018, the European project Q-mic has focused on researching quantum microscopy. The results of this work, specifically from the new improved quantum microscope developed by the consortium, have been published in the journal Science Advances. The authors, from the Institute of Photonic Sciences (ICFO) and centers in Italy and Germany, demonstrate that this device uses very low-intensity quantum light to obtain images of samples with a wide field of view, and with greater sensitivity and resolution compared to classical microscopes.
“The Q-MIC microscope is unique in that it has been designed to illuminate the sample with a special type of light, ‘quantum light’. Instead of normal light, where many disordered photons reach the sample, the quantum source developed by our team uses entangled pairs of photons and sends them in small quantities to impact the sample and retrieve information in a more detailed and specific way,” comments Robin Camphausen from ICFO.
Generally, very low-intensity light is used to avoid any permanent damage to the sample, but unfortunately this leads to an increase in background noise and tends to obscure or distort image details. This microscope uses patterns of interference from entangled photons to reconstruct the sample image. By using entangled photons and advanced mathematical algorithms, the level of noise is reduced and the sensitivity of the measurements is increased by more than 25% compared to classical techniques.
To verify an improvement in the image, researchers conducted tests with samples of protein A, a standard diagnostic solution used as a calibration tool. The proteins were deposited on glass slides and illuminated with classical and quantum light. The respective interference patterns were then reconstructed, and it was observed that the quantum technique produced much smoother images with less noise.
“With quantum light, the level of noise is reduced and therefore randomness, obtaining better information about the image, especially at the edges of the sample, which is crucial for recognizing concentrations, depths, and heights,” summarizes Álvaro Cuevas, co-author of the ICFO study.
The results obtained are promising and indicate a completely new way of obtaining images using this technique. Valerio Pruneri, another co-author from ICFO, highlighted that the innovative device not only has impressive capabilities but can also be exploited in various applications, including materials science, surface analysis for flexible electronics quality, and quantum cryptography for secure communications.
Referrer: MiMub in Spanish
