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Quantum information science is an interdisciplinary field that seeks to understand the analysis, processing, and transmission of information using quantum mechanics principles. It combines the study of Information science with quantum effects in physics. It includes theoretical issues in computational models and more experimental topics in quantum physics, including what can and cannot be done with quantum information. The term quantum information theory is also used, but it fails to encompass experimental research, and can be confused with a subfield of quantum information science that addresses the processing of quantum information.
To understand quantum teleportation, quantum entanglement and the manufacturing of quantum computer hardware requires a thorough understanding of quantum physics and engineering. Since 2010s, there has been remarkable progress in the manufacturing quantum computers, with companies like Google and IBM investing heavily in quantum computer hardware research. Today, it is possible to build a quantum computer with more than 100 qubits. However, the error rate is very large due to the lack of material suitable for the manufacture of quantum computers. Majorana fermions may be one of the key materials lacking (Chiu et al., Rev. Mod. Phys. 88, 2016.) .
Devices for quantum cryptography have already been commercialized. There is an old cipher called a one time pad widely used among spies in the Cold War era. It uses a long sequence of random keys. If two people exchanged the same random keys safely, it is possible to decrypt a one time pad only by accident. However, key exchanging problems can be solved by using quantum entangled particle pairs in the exchange. Quantum mechanical laws such as the no-cloning theorem and wave function collapse provide the basis for secure exchange of random keys. Therefore the manufacturing of devices that can transport quantum entangled particles is an important scientific and engineering goal.
Quantum algorithm and quantum complexity theory are two of the subjects in algorithms and computational complexity theory. In 1994, mathematician Peter Shor published his prime factorization algorithm. If one has a 4,000 logical qubits quantum computer, one can threaten most widely used ciphers such as RSA and ECC by using Shor's algorithm. It can result in serious security problems for many countries. Therefore, his paper triggered a lot of investment in quantum computing research. Many mathematicians and cryptologists are preparing to enter the quantum computing era. See post quantum cryptography.