Physicists work demonstrates the possibility of the technology of quantum cryptography, using satellites.
A group of physicists under the leadership of Paulo Villoresi (Paolo Villoresi) from the University of Padua in Italy has created a model analogue of the schrödinger’s cat of photons launched into space. These scientists have proved the possibility of using satellites to transmit encrypted messages on the basis of quantum mechanics.
Interference is a physical phenomenon that occurs when overlaying each other several waves. In the case of light these waves are electromagnetic, and their interference leads to a redistribution of light intensity. As light propagates through the elementary particles — photons, interference, in other words, leads to increased or decrease the probability that the photon will be in a certain space at a certain time. In this case the photon is able to interfere with itself, as if separating into two separate interacting with each other state.
Photon interference previously observed in laboratory conditions, however, according to the authors of published articles, quantum phenomena are fair for the conditions in which they were experimentally confirmed. Therefore, the task of physicists was to observe quantum interference of photons at great distances, not previously used in the studies. To do this, physicists have sent a beam of light from the telescope located at the Observatory laser telemetry in Matera (MLRO), to the orbital satellite equipped with reflectors.
To create a quantum interference scientists have separated the photons into two parts, each of which is a kind of alternative state of existence of the photon. Famous model the simultaneous existence of two States is Schrodinger’s cat, which is a superposition — state mixing of the living and dead cat at the same time. In the case of the experiment, the photon is a superposition of two “packages” — alternative photons, passing through complex optical setup with delay in the billionth of a second.
Photon packets are bounced off the reflector of the satellite and returned back to the optical system of the Observatory, where scientists could observe quantum interference. The total distance mileage of photons amounted to an unprecedented five thousand kilometers. Due to the relative velocity of the satellite in the interference pattern occurred changes, which confirmed the theoretical calculations.
Scientists believe that their work demonstrates the possibility of the technology of quantum cryptography, using satellites, which will send through the outer channels, and encryption keys to encode secret information.
