Multi-valued Logic Gates for Quantum Computation

We develop a multi-valued logic for quantum computing for use in multi-level quantum systems, and discuss the practical advantages of this approach for scaling up a quantum computer. Generalizing the methods of binary quantum logic, we establish that arbitrary unitary operations on any number of d-level systems (d > 2) can be decomposed into logic gates that operate on only two systems at a time. We show that such multi-valued logic gates are experimentally feasible in the context of the linear ion trap scheme for quantum computing. By using d levels in each ion in this scheme, we reduce the number of ions needed for a computation by a factor of log d.Comment: Revised version; 8 pages, 3 figures; to appear in Physical Review

Selective And Efficient Excitation Of A Diatomic Molecule By A Train Of Weak Ultrashort Pulses

I show that a train of weak ultrashort pulses can selectively and efficiently transfer population between electronic states of a diatomic molecule. Almost 100% transfer between the ground and an excited vibrational state is demonstrated. © 2008 Optical Society of America.De Araujo, L.E.E., Selective and efficient excitation of diatomic molecules by an ultrashort pulse train (2008) Phys. Rev. A, 77, p. 03341

Electromagnetically-induced Phase Grating

Exploiting the giant Kerr nonlinearity associated with electromagnetically induced transparency, an atomic phase grating created with arbitrarily weak fields is proposed. Almost 30% of a probe beam can be diffracted into the first diffraction order. © 2009 Optical Society of America.Fleischhauer, M., Electromagnetically induced transparency: Optics in coherent media (2005) Rev. Mod. Phys., 77, p. 633Ling, H.Y., Li, Y.-Q., Xiao, M., Electromagnetically induced grating: Homogeneously broadened medium (1998) Phys. Rev. A, 57, p. 1338Brown, A.W., Xiao, M., All-optical switching and routing based on an electromagnetically induced absorption grating (2005) Opt. Lett., 30, p. 699Schmidt, H., Imamoglu, A., Giant Kerr nonlinearities obtained by electromagnetically induced transparency (1996) Opt. Lett., 21, p. 1936de Araujo, L.E.E., Electromagnetically induced phase grating (2010) Opt. Lett., 35, p. 97

Measuring Vortex Charge With A Triangular Aperture

We measure the charge of vortex beams (up to ± 7) via diffraction in a triangular aperture. We also apply this technique for measuring femtosecond vortices and non-integer vortices. The results compare favorably with numerical modeling. © 2011 OSA.Padgett, M., Allen, L., Light with a twist in its tail (2000) Contemp. Physics, 41, p. 275Reicherter, M., Haist, T., Wagemann, E.U., Tiziani, H.J., Optical particle trapping with computer-generated holograms written on a liquid-crystal display (1999) Opt. Lett., 24, p. 608Leach, J., Yao, E., Padgett, M.J., Observation of the vortex structure of a non-integer vortex beam (2004) New J. Phys., 6, p. 71Hickmann, J.M., Fonseca, E.J.S., Soares, W.C., Chávez-Cerda, S., Unveiling a truncated optical lattice associated with a triangular aperture using light's orbital angular momentum (2010) Phys. Rev. Lett., 105, p. 05390

Measuring The Topological Charge Of Ultra-broadband, Optical-vortex Beams With A Triangular Aperture

A technique for determining the topological charge of supercontinuum optical vortices is presented. Spatial dispersion is compensated with a unique double-pass arrangement, and charge is consistently measured across a wide range of colors by observing diffraction through a triangular aperture. © OSA 2012.Bezuhanov, K., Dreischuh, A., Paulus, G.G., Schätzel, M.G., Walther, H., Vortices in femtosecond laser fields (1944) Opt. Lett., 29, pp. 1942-1944Mariyenko, I.G., Strohaber, J., Uiterwaal, C.J.G.J., Creation of optical vortices in femtosecond pulses (7608) Opt. Exp., 13, pp. 7599-7608Bezuhanov, K., Dreischuh, A., Paulus, G.G., Schätzel, M.G., Walther, H., Neshev, D., Królikowski, W., Kivshar, Y., Spatial phase dislocations in femtosecond laser pulses (2006) J. Opt. Soc. Am. B, 23, pp. 26-35Zeylikovich, I., Sztul, H.I., Kartazaev, V., Le, T., Alfano, R.R., Ultrashort Laguerre-Gaussian pulses with angular and group velocity dispersion compensation (2027) Opt. Lett., 32, pp. 2025-2027Hickmann, J.M., Fonseca, E.J.S., Soares, W.C., Chavez-Cerda, S., Unveiling a Truncated Optical Lattice Associated with a Triangular Aperture Using Light's Orbital Angular Momentum (2010) Phys. Rev. Lett., 105, p. 053904De Araujo, L.E.E., Anderson, M.E., Measuring vortex charge with a triangular aperture (2011) Opt. Lett., 36, pp. 787-78

Dark State Resonances In A Ca Hollow Cathode Lamp

We observed dark state resonances in Ca vapor from a hollow cathode lamp. Detection via the optogalvanic signal from the lamp was found to be much more sensitive than via a standard optical detection. © 2006 Optical Society of America