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dc.contributor.authorHiggins, BL
dc.contributor.authorBerry, DW
dc.contributor.authorBartlett, SD
dc.contributor.authorWiseman, HM
dc.contributor.authorPryde, GJ
dc.date.accessioned2017-05-03T15:07:55Z
dc.date.available2017-05-03T15:07:55Z
dc.date.issued2007
dc.date.modified2009-09-24T05:55:17Z
dc.identifier.issn0028-0836
dc.identifier.doi10.1038/nature06257
dc.identifier.urihttp://hdl.handle.net/10072/17413
dc.description.abstractMeasurement underpins all quantitative science. A key example is the measurement of optical phase, used in length metrology and many other applications. Advances in precision measurement have consistently led to important scientific discoveries. At the fundamental level, measurement precision is limited by the number N of quantum resources (such as photons) that are used. Standard measurement schemes, using each resource independently, lead to a phase uncertainty that scales as 1/ffiNffiffiffi p -known as the standard quantum limit. However, it has long been conjectured1,2 that it should be possible to achieve a precision limited only by the Heisenberg uncertainty principle, dramatically improving the scaling to 1/N (ref. 3). It is commonly thought that achieving this improvement requires the use of exotic quantum entangled states, such as the NOON state4,5. These states are extremely difficult to generate. Measurement schemes with counted photons or ions have been performed with N#6 (refs 6-15), but few have surpassed the standard quantum limit12,14 and none have shown Heisenberg-limited scaling. Here we demonstrate experimentally a Heisenberg-limited phase estimation procedure. We replace entangled input states with multiple applications of the phase shift on unentangled single-photon states. We generalize Kitaev's phase estimation algorithm16 using adaptive measurement theory17-20 to achieve a standard deviation scaling at the Heisenberg limit. For the largest number of resources used (N5378), we estimate an unknown phase with a variance more than 10 dB below the standard quantum limit; achieving this variance would require more than 4,000 resources using standard interferometry. Our results represent a drastic reduction in the complexity of achieving quantum-enhanced measurement precision.
dc.description.peerreviewedYes
dc.description.publicationstatusYes
dc.format.extent740566 bytes
dc.format.mimetypeapplication/pdf
dc.languageEnglish
dc.language.isoeng
dc.publisherNature Publishing Group
dc.publisher.placeEngland
dc.publisher.urihttp://www.nature.com/nature/index.html
dc.relation.ispartofstudentpublicationN
dc.relation.ispartofpagefrom393
dc.relation.ispartofpageto397
dc.relation.ispartofissue7168
dc.relation.ispartofjournalNature
dc.relation.ispartofvolume450
dc.rights.retentionY
dc.subject.fieldofresearchcode240402
dc.titleEntanglement-free Heisenberg-limited phase estimation
dc.typeJournal article
dc.type.descriptionC1 - Articles
dc.type.codeC - Journal Articles
gro.facultyGriffith Sciences, School of Natural Sciences
gro.rights.copyright© 2007 Nature Publishing Group. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
gro.date.issued2007
gro.hasfulltextFull Text
gro.griffith.authorWiseman, Howard M.
gro.griffith.authorPryde, Geoff


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