View source for Interaction-free measurement

{{short description|Non-invasive measurement of a quantum system}}

In [[physics]], '''interaction-free measurement''' is a type of [[measurement in quantum mechanics]] that detects the position, presence, or state of an object without an interaction occurring between it and the measuring device. Examples include the [[Renninger negative-result experiment]],<ref>{{cite journal | last=Renninger | first=M. |author-link=Mauritius Renninger| title=Zum Wellen-Korpuskel-Dualismus | journal=[[Zeitschrift für Physik]] | publisher=Springer Science and Business Media LLC | volume=136 | issue=3 | year=1953 | issn=1434-6001 | doi=10.1007/bf01325679 | pages=251–261 | bibcode=1953ZPhy..136..251R | s2cid=123122734 | language=de}}</ref> the [[Elitzur–Vaidman bomb-testing problem]],<ref>{{Cite journal|last1=Elitzur|first1=Avshalom C.|author-link1=Avshalom Elitzur|last2=Vaidman|first2=Lev|author-link2=Lev Vaidman|date=1993-07-01|title=Quantum mechanical interaction-free measurements|journal=Foundations of Physics|language=en|volume=23|issue=7|pages=987–997|doi=10.1007/BF00736012|issn=0015-9018|arxiv=hep-th/9305002|bibcode=1993FoPh...23..987E|citeseerx=10.1.1.263.5508|s2cid=18707734}}</ref> and certain double-cavity optical systems, such as [[Hardy's paradox]].

In [[quantum computation]] such measurements are referred to as [[counterfactual quantum computation]],<ref name=MitchinsonJozsa>{{cite journal|last1=Mitchison|first1=Graeme|last2=Jozsa|first2=Richard|title=Counterfactual computation|journal=Proceedings of the Royal Society of London A|date=May 8, 2001|volume=457|issue=2009|pages=1175–1193|doi=10.1098/rspa.2000.0714|arxiv=quant-ph/9907007|bibcode=2001RSPSA.457.1175M|citeseerx=10.1.1.251.9270|s2cid=16208575}}</ref> an idea introduced by physicists [[Graeme Mitchinson]] and [[Richard Jozsa]]. Examples include Keith Bowden's Counterfactual Mirror Array,<ref name=Bowden1>Bowden, Keith G, "Classical Computation can be Counterfactual", in Aspects I, Proc ANPA19, Cambridge 1997 (published May 1999), {{ISBN|0-9526215-3-3}}</ref> describing a digital computer that could be counterfactually interrogated to calculate whether a light beam would fail to pass through a maze.<ref name="Bowden2">{{Cite web 
 |url=http://nonlocal.com/quantum-d/v2/kbowden_03-15-97.html 
 |author=Bowden, Keith 
 |title=Can Schrodinger's Cat Collapse the Wavefunction? 
 |accessdate=2007-12-08 
 |date=1997-03-15 
 |url-status=dead 
 |archiveurl=https://web.archive.org/web/20071016121316/http://nonlocal.com/quantum-d/v2/kbowden_03-15-97.html 
 |archivedate=2007-10-16 
 }}</ref>

Initially proposed as thought experiments by R. H. Dicke in 1981<ref>{{cite journal | last=Dicke | first=R. H. | title=Interaction-free quantum measurements: A Paradox? | journal=American Journal of Physics | volume=49 | issue=10 | pages=925–930 | year=1981 | doi=10.1119/1.12592 | bibcode=1981AmJPh..49..925D | url=https://courses.washington.edu/ega/more_papers/Dicke.pdf}}</ref>
, interaction-free measurements have been experimentally demonstrated in various configurations.<ref>{{Cite journal|last1=Kwiat|first1=Paul|last2=Weinfurter|first2=Harald|last3=Herzog|first3=Thomas|last4=Zeilinger|first4=Anton|last5=Kasevich|first5=Mark A.|date=1995-06-12|title=Interaction-Free Measurement|journal=Physical Review Letters|volume=74|issue=24|pages=4763–4766|doi=10.1103/PhysRevLett.74.4763|pmid=10058593|bibcode=1995PhRvL..74.4763K|citeseerx=10.1.1.561.6205}}</ref><ref>{{Cite journal|last=White|first=Andrew G.|author-link=Andrew G. White|date=1998|title="Interaction-free" imaging|journal=Physical Review A|volume=58|issue=1|pages=605–613|doi=10.1103/PhysRevA.58.605|arxiv=quant-ph/9803060|bibcode=1998PhRvA..58..605W|s2cid=125768139}}</ref><ref>{{Cite journal|last1=Tsegaye|first1=T.|last2=Goobar|first2=E.|last3=Karlsson|first3=A.|last4=Björk|first4=G.|last5=Loh|first5=M. Y.|last6=Lim|first6=K. H.|date=1998-05-01|title=Efficient interaction-free measurements in a high-finesse interferometer|journal=Physical Review A|volume=57|issue=5|pages=3987–3990|doi=10.1103/PhysRevA.57.3987|bibcode=1998PhRvA..57.3987T}}</ref>

Interaction-free measurements have also been proposed as a way to reduce sample damage in [[electron microscopy]].<ref>{{Cite journal|last=Putnam|first=William P.|date=2009|title=Noninvasive electron microscopy with interaction-free quantum measurements|journal=Physical Review A|volume=80|issue=4|pages=040902|doi=10.1103/PhysRevA.80.040902|bibcode=2009PhRvA..80d0902P|doi-access=free|hdl=1721.1/52312|hdl-access=free}}</ref><ref>{{Cite journal|last1=Kruit|first1=P.|last2=Hobbs|first2=R.G.|last3=Kim|first3=C-S.|last4=Yang|first4=Y.|last5=Manfrinato|first5=V.R.|last6=Hammer|first6=J.|last7=Thomas|first7=S.|last8=Weber|first8=P.|last9=Klopfer|first9=B.|date=May 2016|title=Designs for a quantum electron microscope|journal=Ultramicroscopy|volume=164|pages=31–45|doi=10.1016/j.ultramic.2016.03.004|pmid=26998703|issn=0304-3991|arxiv=1510.05946|s2cid=22658047}}</ref>

== Counterfactual quantum communication ==
{{Expand section|date=January 2021}}
In 2012 the idea of counterfactual quantum communication has been proposed and demonstrated.<ref>{{cite journal | last1=Liu | first1=Yang | last2=Ju | first2=Lei | last3=Liang | first3=Xiao-Lei | last4=Tang | first4=Shi-Biao | last5=Tu | first5=Guo-Liang Shen | last6=Zhou | first6=Lei | last7=Peng | first7=Cheng-Zhi | last8=Chen | first8=Kai | last9=Chen | first9=Teng-Yun | last10=Chen | first10=Zeng-Bing | last11=Pan | first11=Jian-Wei |display-authors=5| title=Experimental Demonstration of Counterfactual Quantum Communication | journal=[[Physical Review Letters]] | publisher=American Physical Society (APS) | volume=109 | issue=3 | date=2012-07-19 | issn=0031-9007 | doi=10.1103/physrevlett.109.030501 | page=030501| pmid=22861830 | arxiv=1107.5754 | bibcode=2012PhRvL.109c0501L | s2cid=19114400 }}</ref> Its first achievement was reported in 2017. According to contemporary conceptions of counterfactual quantum communication, information can thereby be exchanged without any physical particle / matter / energy being transferred between the parties, without [[quantum teleportation]] and without the information being the absence of a signal.<ref>{{cite news |title=Scientists Achieve Direct Counterfactual Quantum Communication For The First Time |url=https://futurism.com/scientists-achieve-direct-counterfactual-quantum-communication-for-the-first-time |access-date=16 January 2021 |work=Futurism |language=en}}</ref> In 2020 research suggested that this is based on some form of relation between the properties of modular angular momentum with massless current of modular angular momentum current crossing the "transmission channel" with their interpretation's explanation not being based on "[[Action at a distance|spooky action at a distance]]" but properties of a particle being able to "travel ''[[Quantum nonlocality|locally]]'' through regions from which the particle itself is excluded".<ref>{{cite news |title=Elementary particles part ways with their properties |url=https://phys.org/news/2020-12-elementary-particles-ways-properties.html |access-date=16 January 2021 |work=phys.org |language=en}}</ref><ref>{{cite news |last1=McRae |first1=Mike |title=In a Mind-Bending New Paper, Physicists Give Schrodinger's Cat a Cheshire Grin |url=https://www.sciencealert.com/schrodinger-s-cat-gets-a-cheshire-grin-in-a-mind-bending-quantum-physics-analysis |access-date=16 January 2021 |work=ScienceAlert |language=en-gb}}</ref><ref>{{cite journal |last1=Aharonov |first1=Yakir |last2=Rohrlich |first2=Daniel |title=What Is Nonlocal in Counterfactual Quantum Communication? |journal=Physical Review Letters |date=21 December 2020 |volume=125 |issue=26 |pages=260401 |doi=10.1103/PhysRevLett.125.260401 |pmid=33449741 |arxiv=2011.11667 |bibcode=2020PhRvL.125z0401A |s2cid=145994494 |url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.260401 |access-date=16 January 2021}} [[File:CC-BY icon.svg|50px]] Available on arXiv under [https://creativecommons.org/licenses/by/4.0/ CC BY 4.0].</ref><!--https://arxiv.org/pdf/1909.07530.pdf-->

== See also ==
* [[Counterfactual quantum computation]]
* [[Counterfactual definiteness]]
* [[Quantum nondemolition measurement]]

==References==
<references />

==Bibliography==
# {{cite journal | last=Renninger | first=M. |author-link=Mauritius Renninger| title=Messungen ohne Störung des Meßobjekts |trans-title=Observations without disturbing the object| journal=[[Zeitschrift für Physik]] | publisher=Springer Science and Business Media LLC | volume=158 | issue=4 | year=1960 | issn=1434-6001 | doi=10.1007/bf01327019 | pages=417–421 | bibcode=1960ZPhy..158..417R | s2cid=123027469 | language=de}}
# {{cite journal | last=Renninger | first=M. |author-link=Mauritius Renninger| title=Zum Wellen-Korpuskel-Dualismus | journal=[[Zeitschrift für Physik]] | publisher=Springer Science and Business Media LLC | volume=136 | issue=3 | year=1953 | issn=1434-6001 | doi=10.1007/bf01325679 | pages=251–261 | bibcode=1953ZPhy..136..251R | s2cid=123122734 | language=de}}
# [[Louis de Broglie]], ''The Current Interpretation of Wave Mechanics'', (1964) Elsevier, Amsterdam. ''(Provides discussion of the Renninger experiment.)''
# {{cite journal | last=Dicke | first=R. H. |author-link=Robert H. Dicke| title=Interaction-free quantum measurements: A paradox? | journal=[[American Journal of Physics]] | publisher=American Association of Physics Teachers (AAPT) | volume=49 | issue=10 | year=1981 | issn=0002-9505 | doi=10.1119/1.12592 | pages=925–930| bibcode=1981AmJPh..49..925D }} ''(Provides a recent discussion of the Renninger experiment)''.
# {{cite journal | last=Cramer | first=John G. |author-link=John G. Cramer| title=The transactional interpretation of quantum mechanics | journal=[[Reviews of Modern Physics]] | publisher=American Physical Society (APS) | volume=58 | issue=3 | date=1986-07-01 | issn=0034-6861 | doi=10.1103/revmodphys.58.647 | pages=647–687| bibcode=1986RvMP...58..647C |archive-url=https://web.archive.org/web/20051220195021/http://mist.npl.washington.edu/npl/int_rep/tiqm/TI_40.html|archive-date=2005-12-20|url=http://mist.npl.washington.edu/npl/int_rep/tiqm/TI_40.html| url-access=subscription }} ''(Section 4.1 reviews Renninger's experiment)''.
# Paul G. Kwiat,  [https://web.archive.org/web/20151213154724/http://physics.illinois.edu/people/kwiat/interaction-free-measurements.asp ''The Tao of Quantum Interrogation''],  (2001).
# [[Sean M. Carroll]], [http://cosmicvariance.com/2006/02/27/quantum-interrogation/ ''Quantum Interrogation''] {{Webarchive|url=https://web.archive.org/web/20070203183117/http://cosmicvariance.com/2006/02/27/quantum-interrogation/ |date=2007-02-03 }}, (2006).

==External links==
*{{cite journal|last1=Paige|first1=A. J.|last2=Kwon|first2=Hyukjoon|last3=Simsek|first3=Selwyn|last4=Self|first4=Chris N.|last5=Gray|first5=Johnnie|last6=Kim|first6=M. S.|date=2020-04-30|title=Quantum Delocalized Interactions|journal=Physical Review Letters|volume=125|issue=24|page=240406|doi=10.1103/PhysRevLett.125.240406|pmid=33412066|arxiv=2004.14658|bibcode=2020PhRvL.125x0406P|s2cid=216867791}}

[[Category:Quantum measurement]]
[[Category:Philosophy of physics]]
[[Category:Thought experiments in quantum mechanics]]


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