Editing Quantum Hall effect (section)

== Photonic quantum Hall effect ==
The quantum Hall effect, in addition to being observed in [[2DEG|two-dimensional electron systems]], can be observed in photons. [[Photon]]s do not possess inherent [[electric charge]], but through the manipulation of discrete [[Optical cavity|optical resonators]] and coupling phases or on-site phases, an artificial [[magnetic field]] can be created.<ref>{{Cite journal |last1=Raghu |first1=S. |last2=Haldane |first2=F. D. M. |date=2008-09-23 |title=Analogs of quantum-Hall-effect edge states in photonic crystals |url=https://link.aps.org/doi/10.1103/PhysRevA.78.033834 |journal=Physical Review A |language=en |volume=78 |issue=3 |pages=033834 |doi=10.1103/PhysRevA.78.033834 |arxiv=cond-mat/0602501 |bibcode=2008PhRvA..78c3834R |s2cid=119098087 |issn=1050-2947}}</ref><ref>{{Cite journal |last1=Fang |first1=Kejie |last2=Yu |first2=Zongfu |last3=Fan |first3=Shanhui |date=November 2012 |title=Realizing effective magnetic field for photons by controlling the phase of dynamic modulation |url=http://www.nature.com/articles/nphoton.2012.236 |journal=Nature Photonics |language=en |volume=6 |issue=11 |pages=782–787 |doi=10.1038/nphoton.2012.236 |bibcode=2012NaPho...6..782F |s2cid=33927607 |issn=1749-4885|url-access=subscription }}</ref><ref>{{Cite journal|last1=Schine|first1=Nathan|last2=Ryou|first2=Albert|last3=Gromov|first3=Andrey|last4=Sommer|first4=Ariel|last5=Simon|first5=Jonathan|date=June 2016|title=Synthetic Landau levels for photons|url=http://www.nature.com/articles/nature17943|journal=Nature|language=en|volume=534|issue=7609|pages=671–675|doi=10.1038/nature17943|pmid=27281214|issn=0028-0836|arxiv=1511.07381|bibcode=2016Natur.534..671S|s2cid=4468395}}</ref><ref>{{Cite journal |last1=Minkov |first1=Momchil |last2=Savona |first2=Vincenzo |date=2016-02-20 |title=Haldane quantum Hall effect for light in a dynamically modulated array of resonators |url=https://opg.optica.org/abstract.cfm?URI=optica-3-2-200 |journal=Optica |language=en |volume=3 |issue=2 |pages=200 |doi=10.1364/OPTICA.3.000200 |bibcode=2016Optic...3..200M |s2cid=1645962 |issn=2334-2536|doi-access=free |arxiv=1507.04541 }}</ref><ref>{{Cite journal |last1=Dutt |first1=Avik |last2=Lin |first2=Qian |last3=Yuan |first3=Luqi |last4=Minkov |first4=Momchil |last5=Xiao |first5=Meng |last6=Fan |first6=Shanhui |date=2020-01-03 |title=A single photonic cavity with two independent physical synthetic dimensions |url=https://www.science.org/doi/10.1126/science.aaz3071 |journal=Science |language=en |volume=367 |issue=6473 |pages=59–64 |doi=10.1126/science.aaz3071 |pmid=31780626 |arxiv=1909.04828 |bibcode=2020Sci...367...59D |s2cid=202558675 |issn=0036-8075}}</ref> This process can be expressed through a metaphor of photons bouncing between multiple mirrors. By shooting the light across multiple mirrors, the photons are routed and gain additional phase proportional to their [[Angular momentum operator|angular momentum]]. This creates an effect like they are in a [[magnetic field]].