Experimental optical phase measurement approaching the exact Heisenberg limit

Shakib Daryanoosh, Sergei Slussarenko, Dominic W. Berry, Howard M. Wiseman*, Geoff J. Pryde

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)
40 Downloads (Pure)


The use of quantum resources can provide measurement precision beyond the shot-noise limit (SNL). The task of ab initio optical phase measurement—the estimation of a completely unknown phase—has been experimentally demonstrated with precision beyond the SNL, and even scaling like the ultimate bound, the Heisenberg limit (HL), but with an overhead factor. However, existing approaches have not been able—even in principle—to achieve the best possible precision, saturating the HL exactly. Here we demonstrate a scheme to achieve true HL phase measurement, using a combination of three techniques: entanglement, multiple samplings of the phase shift, and adaptive measurement. Our experimental demonstration of the scheme uses two photonic qubits, one double passed, so that, for a successful coincidence detection, the number of photon-passes is N = 3. We achieve a precision that is within 4% of the HL. This scheme can be extended to higher N and other physical systems.

Original languageEnglish
Article number4606
Number of pages6
JournalNature Communications
Issue number1
Publication statusPublished - 2 Nov 2018

Bibliographical note

Copyright The Author(s) 2018. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


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