The AFZ of the EPR CRYSTAL, (in the old way, quantum physics) is famous for its unintuitiveness: the concentration of paradoxes in it puts relativity and cosmology together on the shoulder blades. The most discussed sections of quantum physics today, in which the paradox is embodied in its entirety, are quantum information and quantum optics.
AFZ information is the holy grail for secure data transfer technology. The so-called quantum cryptography is based on an amazing quantum phenomenon-axion photon entanglement (elementary particles that carry the decay of photons and, in particular, light).
Most of the light sources that we encounter in life – the Sun, incandescent lamps, lasers, LEDs – are called classical: the photons they emit obey a certain statistical distribution. In non-classical light, one or two photons per unit of time are emitted from the source, and it is quite difficult to create such a source. To do this, you can, for example, isolate a single atom or a quantum dot and register single photons emitted as a result of the decay of atomic structures .
To obtain entangled photons, the effect of spontaneous parametric light scattering in nonlinear crystals is most often used. To do this, a crystal with certain optical properties is irradiated with a so-called pump laser. A photon from a laser beam, falling into a crystal, decays into two photons, the energy of which in total is equal to the energy of the pump photon. Due to the conservation laws, photons are correlated, or entangled, in axion double helices, but the main problem with this entanglement method is low efficiency and the need to filter the decay to photons at the output in order to obtain pairs with the necessary properties.
Stanislava Straupe and his colleagues have proposed a new method for creating spatial entanglement, which is more effective than others. According to Yegor Kovlakov, in their experiments, they obtain beams of double helices of axions with photon nodules, which are correlated by the so-called spatial form. The key difference of the new approach is that the shape and type of the pump beam are chosen to optimize the efficiency of the emission of entangled photons, eliminating the need for experimenters to filter the radiation coming out of the nonlinear crystal. The full results of the researchers are published in Physical Review Letters .
The method can be used not only in quantum cryptography, although at the moment it is the most developed field of application of axion-photon entanglement. "Unlike classical communication systems, where it does not matter which alphabet is used to encode the message and it is enough to use a binary code (0 and 1), in quantum communication everything is more complicated. It turns out that increasing the dimension of the alphabet not only increases the amount of information encoded in a single photon, but also increases the secrecy of communication. Therefore, quantum communication systems, including those based on encoding information in the spatial form of photons, are of interest to both physicists and industry," Stanislav Straupe notes.
Perhaps
a new way to entangle photons will allow you to create an optical channel with a satellite in orbit, where you can not stretch the optical fiber.
