Transfer of optical orbital angular momentum to a bound electron.
Photons can carry angular momentum, not only due to their spin, but also due to their spatial structure. This extra twist has been used, for example, to drive circular motion of microscopic particles in optical tweezers as well as to create vortices in quantum gases. Here we excite an atomic transition with a vortex laser beam and demonstrate the transfer of optical orbital angular momentum to the valence electron of a single trapped ion. We observe strongly modified selection rules showing that an atom can absorb two quanta of angular momentum from a single photon: one from the spin and another from the spatial structure of the beam. Furthermore, we show that parasitic ac-Stark shifts from off-resonant transitions are suppressed in the dark centre of vortex beams. These results show how light's spatial structure can determine the characteristics of light-matter interaction and pave the way for its application and observation in other systems.
QUANTUM, Institut für Physik, Universität Mainz, Staudingerweg 7, Mainz, 55128, Germany. schmiegelow@df.uba.ar.|Present address: Departamento de Física, FCEyN, UBA and IFIBA, Conicet, Pabellón 1, Ciudad Universitaria, 1428 Buenos Aires, Argentina, . schmiegelow@df.uba.ar.
Christian T
CT
Schmiegelow
QUANTUM, Institut für Physik, Universität Mainz, Staudingerweg 7, Mainz, 55128, Germany.
Jonas
J
Schulz
QUANTUM, Institut für Physik, Universität Mainz, Staudingerweg 7, Mainz, 55128, Germany.
Henning
H
Kaufmann
QUANTUM, Institut für Physik, Universität Mainz, Staudingerweg 7, Mainz, 55128, Germany.
Thomas
T
Ruster
QUANTUM, Institut für Physik, Universität Mainz, Staudingerweg 7, Mainz, 55128, Germany.
Ulrich G
UG
Poschinger
QUANTUM, Institut für Physik, Universität Mainz, Staudingerweg 7, Mainz, 55128, Germany.
Ferdinand
F
Schmidt-Kaler
Nat Commun. 2014 Jul 30;5:4502
25073906
Phys Rev Lett. 1995 Jul 31;75(5):826-829
10060128
Nature. 2015 Sep 24;525(7570):504-6
26399831
Nature. 2001 Jul 19;412(6844):313-6
11460157
Phys Rev Lett. 2002 Jan 28;88(4):043601
11801120
Phys Rev A. 1992 Jun 1;45(11):8185-8189
9906912
Phys Rev Lett. 2006 Oct 27;97(17):170406
17155450
Science. 1967 Oct 13;158(3798):214-21
17839496
Phys Rev Lett. 2002 Sep 30;89(14):143601
12366045
Opt Express. 2013 Feb 25;21(4):3941-5
23481929
Nature. 2001 Nov 1;414(6859):49-51
11689937
Phys Rev Lett. 2010 Apr 23;104(16):163901
20482049
Phys Rev Lett. 1986 Oct 6;57(14):1696-1698
10033521
Nature. 2010 Sep 16;467(7313):301-4
20844532
Opt Express. 2009 Jun 8;17(12):9718-23
19506621
Opt Express. 2013 Aug 26;21(17):20230-9
24105568
Phys Rev Lett. 2003 Apr 11;90(14):143602
12731916