# Quantum information science

Quantum information science is an area of study about information science related to quantum effects in physics. It includes theoretical issues in computational models as well as 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 in the area and can be confused with a subfield of quantum information science that studies the processing of quantum information.

## Scientific and engineering studies

Quantum teleportation, Quantum entanglement and manufacturing a hardware of quantum computer are just physical and engineering study. They require serious understanding in quantum physics and engineering. Compared to before 2010s, there were some remarkable progresses in manufacturing quantum computer. Google and IBM are investing heavily in quantum computer hardware research. More than 100-qubit quantum computer is possible today. The error occurrence is so serious that we cannot say that we have a material suitable for quantum computers yet. Majorana fermion may be one of the key material.

Devices for Quantum cryptography have been commercialized already. There is an old cipher called one time pad. This cipher widely used among the spies in the cold war era. It uses a long sequence of random keys. If two person exchanged same random keys safely, it is impossible to decrypt one time pad except by accident. But key exchanging is not easy. However, the key exchanging problems can be solved by exchanging quantum entangled particle pairs. Quantum mechanical laws such as no cloning theorem and wave function collapse provide secure exchange of random keys. So, manufacturing devices that can transport quantum entangled particles is an important scientific and engineering problem.

Programming languages for quantum computer is also needed. Q Sharp, Qiskit are popular quantum programming languages.

## Related mathematical subjects

Quantum algorithm and Quantum complexity theory are one of the subjects in algorithm and computational complexity theory. In 1994, a mathematician Peter Shor published his prime factorization algorithm. If one has 1000-qubit quantum computer, one can threat most widely used ciphers such as RSA and ECC by Shor's algorithm. It can be a serious security problems for many countries. Therefore, his paper triggered a lot of investment in quantum computing research. Many mathematicians and cryptologists preparing to quantum computing era. See post quantum cryptography.