title: Photonic polarization gears for ultra-sensitive angular measurements.
abstract: Quantum metrology bears a great promise in enhancing measurement precision, but is unlikely to become practical in the near future. Its concepts can nevertheless inspire classical or hybrid methods of immediate value. Here we demonstrate NOON-like photonic states of m quanta of angular momentum up to m=100, in a setup that acts as a 'photonic gear', converting, for each photon, a mechanical rotation of an angle θ into an amplified rotation of the optical polarization by mθ, corresponding to a 'super-resolving' Malus' law. We show that this effect leads to single-photon angular measurements with the same precision of polarization-only quantum strategies with m photons, but robust to photon losses. Moreover, we combine the gear effect with the quantum enhancement due to entanglement, thus exploiting the advantages of both approaches. The high 'gear ratio' m boosts the current state of the art of optical non-contact angular measurements by almost two orders of magnitude.
authors.affiliation: Dipartimento di Fisica, Sapienza Università di Roma, piazzale Aldo Moro 5, 00185 Roma, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: D'Ambrosio
authors.forename: Nicolò
authors.initials: N
authors.lastname: Spagnolo
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Del Re
authors.forename: Sergei
authors.initials: S
authors.lastname: Slussarenko
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Leong Chuan
authors.initials: LC
authors.lastname: Kwek
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Marrucci
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Walborn
authors.forename: Leandro
authors.initials: L
authors.lastname: Aolita
authors.forename: Fabio
authors.initials: F
authors.lastname: Sciarrino
references.citation: Opt Express. 2009 May 11;17(10):8287-93
references.pmid: 19434161
references.citation: Science. 2009 May 29;324(5931):1166-8
references.pmid: 19389997
references.citation: Science. 2010 May 14;328(5980):879-81
references.pmid: 20466927
references.citation: Phys Rev Lett. 2006 Apr 28;96(16):163905
references.pmid: 16712234
references.citation: Opt Lett. 2005 Feb 1;30(3):242-4
references.pmid: 15751872
references.citation: Phys Rev Lett. 2009 Jul 3;103(1):013601
references.pmid: 19659145
references.citation: Nat Commun. 2012;3:1063
references.pmid: 22990859
references.citation: Appl Opt. 2012 Apr 1;51(10):C1-6
references.pmid: 22505084
references.citation: Nat Commun. 2012 Jul 17;3:961
references.pmid: 22805568
references.citation: Phys Rev Lett. 2012 Jun 8;108(23):233602
references.pmid: 23003955
references.citation: Science. 2012 Nov 2;338(6107):640-3
references.pmid: 23118185
references.citation: Nature. 2006 Sep 21;443(7109):316-9
references.pmid: 16988707
references.citation: Opt Express. 2011 Feb 28;19(5):4085-90
references.pmid: 21369237
references.citation: Nature. 2004 May 13;429(6988):161-4
references.pmid: 15141206
references.citation: Phys Rev Lett. 2012 Mar 2;108(9):090501
references.pmid: 22463620
references.citation: Science. 2007 May 4;316(5825):726-9
references.pmid: 17478715
references.citation: Phys Rev Lett. 2009 Jan 30;102(4):040403
references.pmid: 19257407
references.citation: Nature. 2004 May 13;429(6988):158-61
references.pmid: 15141205
references.citation: Nature. 2005 Dec 1;438(7068):639-42
references.pmid: 16319885
references.citation: Nature. 2007 Nov 15;450(7168):393-6
references.pmid: 18004379
references.citation: Phys Rev Lett. 2006 Oct 27;97(17):170406
references.pmid: 17155450