Physicists from the University of Glasgow have announced a breakthrough in quantum holography, which allows you to create crisp and detailed images, removing interference from unwanted light sources and other external influences. The method is based on the quantum entanglement of the polarizations of photons, when the properties of particles are interdependent, despite the distance separating them. The article of scientists was published in the journal Nature Physics. The groundbreaking research is summarized in a press release on Phys.org.
In conventional holography, an image of an object is most often created using a laser beam, which is split into two beams, called the object and reference beams. The object beam expands and illuminates the subject, reflecting and then falling onto the photographic plate. The reference beam does not touch the object, is reflected from the mirror and also falls on the plate, interacting with the beam reflected from the object, and creating an interference pattern. During exposure, the light sources, the object and the plate must remain motionless relative to each other, otherwise the hologram will be damaged.
For living objects and unstable materials, holography is possible only when using an intense and short pulse of light, which is dangerous and is almost always carried out in laboratories with special equipment.
The new method of quantum holography also uses two beams, but they never interact with each other. A blue laser beam passes through the crystal, splitting it into two beams of entangled photons. When something changes the properties (direction of motion and polarization) of a photon in one beam, it also affects the properties of a photon entangled with it in another. As in classical holography, one beam is used to illuminate an object, thus changing the phases of the light waves in the beam.
The second ray hits the spatial light modulator, which partially slows down the speed of photons passing through it. As a result, light waves acquire a different phase relative to their entangled partners. A hologram is obtained by measuring the correlation between entangled photon positions using separate megapixel digital cameras. A high-quality image of an object is obtained by combining four holograms obtained for four different phase shifts applied by the modulator.
In the experiment, a phase image was obtained for several objects: letters UofG on a liquid crystal display, a bird’s feather and a drop of oil on a microscope slide. Scientists note that quantum holography is free of the shortcomings of classical holography, which allows creating detailed images useful for medical purposes, for example, visualizing the functions of individual cells.