Back action (quantum)

In quantum mechanics, back action refers to the effect of a detector on a measurement. Ideally, a detector should have no influence on the quantity it is measuring. However, in quantum systems it is sometimes the case that back action by the detector is an inherent feature of the system, and not just a result of the detector being imperfect.[1][2] Back action has important consequences for the measurement process, and is a significant factor in measurements near quantum limits, such as measurements approaching the Standard Quantum Limit (SQL).

Back action is an area of active research. Recent experiments with nanomechanical systems have attempted to evade back action while making measurements.[3][4]

References
  1. Braginsky, V .B.; Khalili, F. Ya. (1992). Quantum Measurement. Cambridge University Press. ISBN 978-0521484138
  2. Hatridge, M.; Shankar, S.; Mirrahimi, M.; Schackert, F.; Geerlings, K.; Brecht, T.; Sliwa, K. M.; Abdo, B.; Frunzio, L.; Girvin, S. M.; Schoelkopf, R. J.; Devoret, M. H. (10 January 2013). "Quantum Back-Action of an Individual Variable-Strength Measurement". Science. American Association for the Advancement of Science (AAAS). 339 (6116): 178–181. arXiv:1903.11732. Bibcode:2013Sci...339..178H. doi:10.1126/science.1226897. ISSN 0036-8075. PMID 23307736. S2CID 206543620.
  3. Hertzberg, J. B.; Rocheleau, T.; Ndukum, T.; Savva, M.; Clerk, A. A.; Schwab, K. C. (6 December 2009). "Back-action-evading measurements of nanomechanical motion". Nature Physics. Springer Science and Business Media LLC. 6 (3): 213–217. arXiv:0906.0967. doi:10.1038/nphys1479. ISSN 1745-2473. S2CID 34386965.
  4. Møller, Christoffer B.; Thomas, Rodrigo A.; Vasilakis, Georgios; Zeuthen, Emil; Tsaturyan, Yeghishe; Balabas, Mikhail; Jensen, Kasper; Schliesser, Albert; Hammerer, Klemens; Polzik, Eugene S. (July 2017). "Quantum back-action-evading measurement of motion in a negative mass reference frame". Nature. 547 (7662): 191–195. arXiv:1608.03613. Bibcode:2017Natur.547..191M. doi:10.1038/nature22980. PMID 28703182. S2CID 4460356.


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