Editing Quantum information (section)

{{short description|Information held in the state of a quantum system}}
{{for|the journal|npj Quantum Information}}
[[File:Qubits_(5940500587).jpg|thumb|upright=1|Optical lattices use lasers to separate rubidium atoms (red) for use as information bits in neutral-atom quantum processors—prototype devices which designers are trying to develop into full-fledged quantum computers.]]
'''Quantum information''' is the [[information]] of the [[quantum state|state]] of a [[quantum system]]. It is the basic entity of study in [[Quantum information science|quantum information theory]],<ref name="Vedral2006"/><ref name="Nielsen2010"/><ref name="Hayashi2006"/> and can be manipulated using [[quantum information processing]] techniques. Quantum information refers to both the technical definition in terms of [[Von Neumann entropy]] and the general computational term.

It is an interdisciplinary field that involves [[quantum mechanics]], [[computer science]], [[information theory]], [[philosophy]] and [[cryptography]] among other fields.<ref name="Bokulich2010"/><ref name="Benatti2010"/><ref name="Benatti2009"/> Its study is also relevant to disciplines such as [[cognitive science]], [[psychology]] and [[neuroscience]].<ref name="Hayashi2015"/><ref name="Hayashi2017"/><ref name="Georgiev2017"/><ref name="Georgiev2020"/> Its main focus is in extracting information from matter at the microscopic scale. Observation in science is one of the most important ways of acquiring information and measurement is required in order to quantify the observation, making this crucial to the [[scientific method]]. In [[quantum mechanics]], due to the [[uncertainty principle]], [[Commutative property|non-commuting]] [[Observable|observables]] cannot be precisely measured simultaneously, as an [[Quantum state|eigenstate]] in one basis is not an eigenstate in the other basis. According to the eigenstate–eigenvalue link, an observable is well-defined (definite) when the state of the system is an eigenstate of the observable.<ref name="Gilton2016">{{cite journal
 | author = Gilton, Marian J. R.
 | title = Whence the eigenstate–eigenvalue link?
 | journal = Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics
 | volume = 55
 | pages = 92–100
 | doi = 10.1016/j.shpsb.2016.08.005
 | year = 2016
| bibcode = 2016SHPMP..55...92G
 }}</ref> Since any two non-commuting observables are not simultaneously well-defined, a quantum state can never contain definitive information about both non-commuting observables.<ref name="Hayashi2017" />

Data can be encoded into the [[State (computer science)|quantum state]] of a quantum system as [[quantum information]].<ref name="Preskill2018"/> While quantum mechanics deals with examining properties of matter at the microscopic level,<ref name="Feynman2013"/><ref name="Hayashi2017" /> [[quantum information science]] focuses on extracting information from those properties,<ref name="Hayashi2017" /> and [[Quantum computing|quantum computation]] manipulates and processes information – performs logical operations – using [[quantum information processing]] techniques.<ref name="Lo1998"/>

Quantum information, like classical information, can be processed using [[digital computer]]s, [[communications channel|transmitted]] from one location to another, manipulated with [[algorithm]]s, and analyzed with computer science and [[mathematics]]. Just like the basic unit of classical information is the bit, quantum information deals with [[Qubit|qubits]].<ref name="Bennett1998"/> Quantum information can be measured using Von Neumann entropy.

Recently, the field of [[quantum computing]] has become an active research area because of the possibility to disrupt modern computation, communication, and [[cryptography]].<ref name="Lo1998"/><ref name="Garlinghouse2020"/>