In the next years we have to handle the problems originated from the decreasing size of microchips. As everyday life is getting faster it requires researchers and engineers to respond to the growing needs. In telecommunication applications one of the most crucial issue to solve is how to transmit as many bytes at a given frequency in a second as possible. One way to determine the system’s efficiency is to measure the number of bytes sent per second. In this chapter we presented the base of quantum mechanic based communication. We showed that there exist already algorithms to solve problems which are very difficult to be solved by traditional computers. The quantum theory has appeared in satellite communications offering answers for some of nowadays’ technical questions. We introduced two solutions which can be useful in redundancy-free communications. One of the primary requirements of long-distance and free-space quantum communication is the capability of the effective transmission of quantum states in non-ideal, noisy environments. The free-space and satellite quantum channel could be the way to increase significantly the distance limit of current quantum communication systems. The current earthbound freespace quantum channels have the advantage in that they can be combined with satellite quantum communication. In the future, we will be able to overcome the current distance limits in quantum communication by transmitting EPR-states from space to Earth.
In the next years we have to handle the problems originated from the decreasing size of microchips. As everyday life is getting faster it requires researchers and engineers to respond to the growing needs. In telecommunication applications one of the most crucial issue to solve is how to transmit as many bytes at a given frequency in a second as possible. One way to determine the system’s efficiency is to measure the number of bytes sent per second. In this chapter we presented the base of quantum mechanic based communication. We showed that there exist already algorithms to solve problems which are very difficult to be solved by traditional computers. The quantum theory has appeared in satellite communications offering answers for some of nowadays’ technical questions. We introduced two solutions which can be useful in redundancy-free communications. One of the primary requirements of long-distance and free-space quantum communication is the capability of the effective transmission of quantum states in non-ideal, noisy environments. The free-space and satellite quantum channel could be the way to increase significantly the distance limit of current quantum communication systems. The current earthbound freespace quantum channels have the advantage in that they can be combined with satellite quantum communication. In the future, we will be able to overcome the current distance limits in quantum communication by transmitting EPR-states from space to Earth.
Abstract Quantum computing offers revolutionary solutions in the field of computer sciences, applying the opportunities of quantum physics which are incomparably richer than classical physics. Although quantum computers are going to be the tools of the far future, there are already a few algorithms to solve problems which are very difficult to handle with traditional computers. Perhaps the easiest example of a structure of a quantum system is a quantum channel. Typically, one is interested in some basis in the Hilbert space representing the input of a channel, which is entangled with a second Hilbert space representing the environment, and then another (possibly the same) basis for the first space at a later time. Free-space quantum key distribution (QKD)—over an optical path of about 30 cm—was first introduced in 1991, and recent advances have led to demonstrations. Indeed there are certain key distribution problems in this category for which free-space QKD has practical advantages (for example it is not practical to send a courier to a satellite). Quantum computing algorithms can be used to affirm our communication in several ways (open-air communication, satellite communications, satellite broadcast, satellite-satellite communication). We set up a free-space quantum-channel-model at the university and made several simulations. The main aim is to trace some adoptable algorithms in the communication between Earth and the satellite and also between satellites. This paper is a theoretical study to compare the simulation results of the three models.
Quantum computing offers unique solutions applying tools of quantum physics, which are incomparably numerous than those of classical physics. Although quantum computers are the possible application of the far future, a few algorithms are already available for solving problems otherwise difficult to handle with traditional computers. Recently the telecommunication requires large amount of data transfer via satellites. An interesting way of dealing with this problem might be using quantum communication.
Long-distance quantum communication is one of the most important tasks in quantum information science. It contains two main motivations: one is the fundamental interests, and the other is the practical requirements. The physical distance of quantum communication over free-space channel has been extended from several meters in the lab to 1000 km through satellite. In this mini-review, we emphasize the progress made toward the global quantum network, mainly following the world’s first satellite-to-Earth quantum communication in 2017. This includes the development of commercial small-scale quantum satellite constellations and high-orbit satellites capable of all-time coverage, as well as the feasibility of quantum communication network. On this basis, we then discussed the possibility of cross-application of free-space quantum communication technology in fundamental physics, precision measurement, and even astronomical observations. Free-space quantum communication presents both challenges and opportunities, playing a crucial role in the future global quantum network.
Problem statement: The security of the telecommunications satellite has become a crucial issue.The telecommunications can be set using the classical cryptography.But this so-called classical cryptography provides cryptographic security.This means that security is based on the difficulty of some mathematics problems.On the other hand, quantum cryptography provides security without conditions based on the law of quantum physics.This method, called the theoretic information security is evidenced using the theory of information.Approach: In this study, we study whether quantum cryptography can be applied in the frame of the satellite telecommunications network.To do this in our project, we present theories regarding the following issues: Telecommunications Station and Satellite Communication Networks, Quantum Key Distribution, Open Space and Satellites, Analyses in different Scenarios between the Satellite and Earth station.Results: Quantum communications offers many advantages for secure data transmission, in our implementation study, we presented different scenarios of quantum key exchange between satellites and ground stations for possible approach to subsystem with quantum communication in space, capable of generating and detecting entangled photons as well as faint laser pulses.Conclusion: The use of satellites to distribute quantum photon provides a unique solution for long-distance.Moreover, quantum cryptography is a satisfactory solution to improve the safety problem.So, the quantum transmissions are the future of telecommunications.
The primary role played by communication in our society gives importance to the problem of securely transmitting sensitive information. Quantum physics can be exploited to solve this problem in a more secure way than it is possible by using classical protocols. The application of quantum physics to communication tasks is the basis of the new quantum communication field, of which quantum cryptography represents the most successful achievement. Quantum communication, however, suffers the presence of losses much more than classical communication. The high level of losses in fiber-based systems, limiting the maximum transmission distance to a few hundred kilometers, makes it necessary to find new ways to go further. A promising solution for extending it to a worldwide scale seems to be the use of satellites. This thesis studies some aspects of quantum communication from an experimental point of view. It presents both the study in the laboratory of quantum communication protocols and the experimental characterization of the satellite-ground channel by using a simulated space source exploiting corner-cube retro-reflectors on geodesic satellites. In addition to this, it also deals with some more technical issues of the problem, such as the construction of a high brilliance polarization-entangled photon source and the improvement of the receiving station for space quantum communication at the Matera Laser Ranging Observatory.
Quantum key distribution is now a mature quantum communication protocol which allows the verifiably secure sharing of encryption keys between two communicating parties. It seeks to address potential vulnerabilities of data transmission and storage, offering a realistic possibility to share encryption keys which are robust to eavesdropping attacks and future-proof against hacking. Fibre-optic implementations of quantum key distribution currently have a limited practical transmission distance, of less than 400 km, making commercial applications limited. Quantum-specific amplifier/repeater technology is not yet mature enough to increase the transmission distance to achieve global capabilities. Optical fiber is also impractical and expensive for applications where a remote area or moving platform are involved. In recent years, long-distance free-space quantum communications using low-Earth orbit satellites has seen an increase in interest from the academic community as well as from industrial organisations and national research institutes. The source of this new interest was a series of proof-of-principle demonstrations of satellite-based quantum key distribution in 2017. The use of free-space channels implementing airborne or satellite platforms also opens a range of new applications for quantum communications, as they allow coverage of remote areas, moving platforms, and also avoid the requirement of spooling fibre through volatile regions. This presentation will give a general introduction to satellite-based quantum communications, an overview of the field, and discuss future endeavours. The talk will also include an overview of our research into novel photonic technology, such as the use of detector array technology, for the optical ground station receiver.