Editing Uncertainty principle (section)

===Heisenberg limit===
In [[quantum metrology]], and especially [[interferometry]], the '''Heisenberg limit''' is the optimal rate at which the accuracy of a measurement can scale with the energy used in the measurement. Typically, this is the measurement of a phase (applied to one arm of a [[beam-splitter]]) and the energy is given by the number of photons used in an [[interferometer]]. Although some claim to have broken the Heisenberg limit, this reflects disagreement on the definition of the scaling resource.<ref>{{Cite journal | last1 = Giovannetti | first1 = V. | last2 = Lloyd | first2 = S. | last3 = Maccone | first3 = L. | doi = 10.1038/nphoton.2011.35 | title = Advances in quantum metrology | journal = Nature Photonics | volume = 5 | issue = 4 | pages = 222 | year = 2011 | arxiv = 1102.2318 | bibcode = 2011NaPho...5..222G | s2cid = 12591819 }}; [https://arxiv.org/abs/1102.2318 arXiv] {{Webarchive|url=https://web.archive.org/web/20200806200530/https://arxiv.org/abs/1102.2318 |date=2020-08-06 }}</ref> Suitably defined, the Heisenberg limit is a consequence of the basic principles of quantum mechanics and cannot be beaten, although the weak Heisenberg limit can be beaten.<ref>{{Cite journal|last=Luis|first=Alfredo|date=2017-03-13|title=Breaking the weak Heisenberg limit | journal=Physical Review A | language=en|volume=95|issue=3 | pages=032113 | doi=10.1103/PhysRevA.95.032113 | arxiv=1607.07668 | bibcode=2017PhRvA..95c2113L | s2cid=55838380|issn=2469-9926}}</ref>