title: Demonstration of entanglement-enhanced phase estimation in solid.
abstract: Precise parameter estimation plays a central role in science and technology. The statistical error in estimation can be decreased by repeating measurement, leading to that the resultant uncertainty of the estimated parameter is proportional to the square root of the number of repetitions in accordance with the central limit theorem. Quantum parameter estimation, an emerging field of quantum technology, aims to use quantum resources to yield higher statistical precision than classical approaches. Here we report the first room-temperature implementation of entanglement-enhanced phase estimation in a solid-state system: the nitrogen-vacancy centre in pure diamond. We demonstrate a super-resolving phase measurement with two entangled qubits of different physical realizations: an nitrogen-vacancy centre electron spin and a proximal (13)C nuclear spin. The experimental data shows clearly the uncertainty reduction when entanglement resource is used, confirming the theoretical expectation. Our results represent an elemental demonstration of enhancement of quantum metrology against classical procedure.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Gang-Qin
authors.initials: GQ
authors.lastname: Liu
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Yu-Ran
authors.initials: YR
authors.lastname: Zhang
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Yan-Chun
authors.initials: YC
authors.lastname: Chang
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Jie-Dong
authors.initials: JD
authors.lastname: Yue
authors.affiliation: 1] Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [2] Collaborative Innovation Center of Quantum Matter, Beijing 100190, China.
authors.forename: Heng
authors.initials: H
authors.lastname: Fan
authors.affiliation: 1] Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [2] Collaborative Innovation Center of Quantum Matter, Beijing 100190, China.
authors.forename: Xin-Yu
authors.initials: XY
authors.lastname: Pan
references.citation: Phys Rev Lett. 1994 May 30;72(22):3439-3443
references.pmid: 10056200
references.citation: Science. 2007 Jun 1;316(5829):1312-6
references.pmid: 17540898
references.citation: Phys Rev Lett. 2007 Jan 19;98(3):030407
references.pmid: 17358668
references.citation: Nanoscale. 2014 Sep 7;6(17):10134-9
references.pmid: 25042514
references.citation: Science. 2006 Oct 13;314(5797):281-5
references.pmid: 16973839
references.citation: Nature. 2007 Nov 15;450(7168):393-6
references.pmid: 18004379
references.citation: Phys Rev Lett. 2010 Feb 19;104(7):073604
references.pmid: 20366883
references.citation: Science. 2007 May 4;316(5825):726-9
references.pmid: 17478715
references.citation: Nature. 2012 Apr 04;484(7392):82-6
references.pmid: 22481361
references.citation: Nat Nanotechnol. 2014 Mar;9(3):171-6
references.pmid: 24487650
references.citation: Nat Nanotechnol. 2012 Oct;7(10):657-62
references.pmid: 22941402
references.citation: Nature. 2014 Feb 13;506(7487):204-7
references.pmid: 24476818
references.citation: Phys Rev Lett. 2012 Sep 28;109(13):137601
references.pmid: 23030118
references.citation: Phys Rev Lett. 2001 Jun 25;86(26 Pt 1):5870-3
references.pmid: 11415382
references.citation: Science. 2010 May 14;328(5980):879-81
references.pmid: 20466927
references.citation: Phys Rev Lett. 2009 Feb 6;102(5):057403
references.pmid: 19257552
references.citation: Phys Rev Lett. 2004 Sep 24;93(13):130501
references.pmid: 15524692
references.citation: Sci Rep. 2013;3:1498
references.pmid: 23511233
references.citation: Phys Rev Lett. 2012 Sep 28;109(13):137602
references.pmid: 23030119
references.citation: Science. 2008 Jun 6;320(5881):1326-9
references.pmid: 18535240
references.citation: Nature. 2001 Jan 4;409(6816):63-6
references.pmid: 11343111
references.citation: Phys Rev Lett. 2010 Jul 23;105(4):040504
references.pmid: 20867828
references.citation: Phys Rev Lett. 2012 May 25;108(21):210404
references.pmid: 23003224
references.citation: Sci Rep. 2012;2:432
references.pmid: 22666535
references.citation: Science. 2010 Jul 30;329(5991):542-4
references.pmid: 20595582
references.citation: Phys Rev Lett. 2012 Aug 17;109(7):070502
references.pmid: 23006348
references.citation: Phys Rev Lett. 2013 Feb 8;110(6):060502
references.pmid: 23432227
references.citation: Nat Commun. 2013;4:2254
references.pmid: 23912335
references.citation: Science. 2012 Jun 8;336(6086):1283-6
references.pmid: 22679092
references.citation: Phys Rev Lett. 2006 Jan 13;96(1):010401
references.pmid: 16486424
references.citation: Nature. 2011 Sep 21;477(7366):574-8
references.pmid: 21937989
references.citation: Phys Rev Lett. 2014 Mar 14;112(10):103604
references.pmid: 24679294