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Miles J. Padgett - One of the best experts on this subject based on the ideXlab platform.
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Orbital Angular Momentum 25 years on invited
Optics Express, 2017Co-Authors: Miles J. PadgettAbstract:Twenty-five years ago Allen, Beijersbergen, Spreeuw, and Woerdman published their seminal paper establishing that light beams with helical phase-fronts carried an Orbital Angular Momentum. Previously Orbital Angular Momentum had been associated only with high-order atomic/molecular transitions and hence considered to be a rare occurrence. The realization that every photon in a laser beam could carry an Orbital Angular Momentum that was in excess of the Angular Momentum associated with photon spin has led both to new understandings of optical effects and various applications. These applications range from optical manipulation, imaging and quantum optics, to optical communications. This brief review will examine some of the research in the field to date and consider what future directions might hold.
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interface between path and Orbital Angular Momentum entanglement for high dimensional photonic quantum information
Nature Communications, 2014Co-Authors: Miles J. Padgett, Martin P J Lavery, Robert Fickler, Radek Lapkiewicz, Marcus Huber, Anton ZeilingerAbstract:The Orbital Angular Momentum of light is a promising degree of freedom for long-distance information transportation. To create high-dimensional entanglement for pairs of photons, Fickler et al. use an optical mode sorter in reverse to transfer entanglement between the path into the Orbital Angular Momentum.
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direct measurement of a 27 dimensional Orbital Angular Momentum state vector
Nature Communications, 2014Co-Authors: Mehul Malik, Jonathan Leach, Miles J. Padgett, Mohammad Mirhosseini, Martin P J Lavery, Robert W BoydAbstract:The measurement of a quantum state poses a unique challenge for experimentalists. Recently, the technique of ‘direct measurement’ was proposed for characterizing a quantum state in situ through sequential weak and strong measurements. While this method has been used for measuring polarization states, its real potential lies in the measurement of states with a large dimensionality. Here we show the practical direct measurement of a highdimensional state vector in the discrete basis of Orbital Angular Momentum. Through weak measurements of Orbital Angular Momentum and strong measurements of Angular position, we measure the complex probability amplitudes of a pure state with a dimensionality, d ¼ 27. Further, we use our method to directly observe the relationship between rotations of a state vector and the relative phase between its Orbital-Angular-Momentum components. Our technique has important applications in high-dimensional classical and quantum information systems and can be extended to characterize other types of large quantum states.
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detection of a spinning object using light s Orbital Angular Momentum
Science, 2013Co-Authors: Martin P J Lavery, Stephen M. Barnett, F C Speirits, Miles J. PadgettAbstract:The linear Doppler shift is widely used to infer the velocity of approaching objects, but this shift does not detect rotation. By analyzing the Orbital Angular Momentum of the light scattered from a spinning object, we observed a frequency shift proportional to product of the rotation frequency of the object and the Orbital Angular Momentum of the light. This rotational frequency shift was still present when the Angular Momentum vector was parallel to the observation direction. The multiplicative enhancement of the frequency shift may have applications for the remote detection of rotating bodies in both terrestrial and astronomical settings.
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quantum correlations in optical angle Orbital Angular Momentum variables
Science, 2010Co-Authors: Jonathan Leach, Stephen M. Barnett, Robert W Boyd, Sonja Frankearnold, B Jack, J Romero, Anand K Jha, Alison M Yao, D G Ireland, Miles J. PadgettAbstract:Entanglement of the properties of two separated particles constitutes a fundamental signature of quantum mechanics and is a key resource for quantum information science. We demonstrate strong Einstein, Podolsky, and Rosen correlations between the Angular position and Orbital Angular Momentum of two photons created by the nonlinear optical process of spontaneous parametric down-conversion. The discrete nature of Orbital Angular Momentum and the continuous but periodic nature of Angular position give rise to a special sort of entanglement between these two variables. The resulting correlations are found to be an order of magnitude stronger than those allowed by the uncertainty principle for independent (nonentangled) particles. Our results suggest that Angular position and Orbital Angular Momentum may find important applications in quantum information science.
Robert W Boyd - One of the best experts on this subject based on the ideXlab platform.
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creating high harmonic beams with controlled Orbital Angular Momentum
Frontiers in Optics, 2014Co-Authors: Genevieve Gariepy, Jonathan Leach, Robert W Boyd, Kyung Taec Kim, T J Hammond, E Frumker, P B CorkumAbstract:We experimentally show that Orbital Angular Momentum (OAM) is conserved during the non-perturbative process of high-harmonic generation and theoretically demonstrate how any value of OAM can be imparted to any harmonic in a controlled manner.
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creating high harmonic beams with controlled Orbital Angular Momentum
Physical Review Letters, 2014Co-Authors: Genevieve Gariepy, Jonathan Leach, Robert W Boyd, Kyung Taec Kim, T J Hammond, E FrumkerAbstract:A beam with an Angular-dependant phase Φ = lϕ about the beam axis carries an Orbital Angular Momentum of lℏ per photon. Such beams are exploited to provide superresolution in microscopy. Creating extreme ultraviolet or soft-x-ray beams with controllable Orbital Angular Momentum is a critical step towards extending superresolution to much higher spatial resolution. We show that Orbital Angular Momentum is conserved during high-harmonic generation. Experimentally, we use a fundamental beam with |l| = 1 and interferometrically determine that the harmonics each have Orbital Angular Momentum equal to their harmonic number. Theoretically, we show how any small value of Orbital Angular Momentum can be coupled to any harmonic in a controlled manner. Our results open a route to microscopy on the molecular, or even submolecular, scale.
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optical spin to Orbital Angular Momentum conversion in ultra thin metasurfaces with arbitrary topological charges
Applied Physics Letters, 2014Co-Authors: Frederic Bouchard, Ebrahim Karimi, Israel De Leon, Sebastian A Schulz, Jeremy Upham, Robert W BoydAbstract:Orbital Angular Momentum associated with the helical phase-front of optical beams provides an unbounded “space” for both classical and quantum communications. Among the different approaches to generate and manipulate Orbital Angular Momentum states of light, coupling between spin and Orbital Angular Momentum allows a faster manipulation of Orbital Angular Momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional Orbital Angular Momentum generators. In this work, we design and fabricate an ultra-thin spin-to-Orbital Angular Momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of Orbital Angular Momentum l. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge q. When a circularly polarised ligh...
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optical spin to Orbital Angular Momentum conversion in ultra thin metasurfaces with arbitrary topological charges
arXiv: Optics, 2014Co-Authors: Frederic Bouchard, Ebrahim Karimi, Israel De Leon, Sebastian A Schulz, Jeremy Upham, Robert W BoydAbstract:Orbital Angular Momentum associated with the helical phase-front of optical beams provides an unbounded \qo{space} for both classical and quantum communications. Among the different approaches to generate and manipulate Orbital Angular Momentum states of light, coupling between spin and Orbital Angular Momentum allows a faster manipulation of Orbital Angular Momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional Orbital Angular Momentum generators. In this work, we design and fabricate an ultra-thin spin-to-Orbital Angular Momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of OAM $\ell$. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge $q$. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the OAM changes in value by $\ell = \pm2q\hbar$ per photon. We experimentally demonstrate $\ell$ values ranging from $\pm 1$ to $\pm 25$ with conversion efficiencies of $8.6\pm0.4~\%$. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations and nano-scale sensing.
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generating optical Orbital Angular Momentum at visible wavelengths using a plasmonic metasurface
Light-Science & Applications, 2014Co-Authors: Ebrahim Karimi, Robert W Boyd, Israel De Leon, Sebastian A Schulz, Jeremy Upham, Hammam QassimAbstract:Visible, circularly polarised light can be transformed into light-carrying Orbital Angular Momentum by a plasmonic metasurface. That is the finding of Ebrahim Karimi and co-workers at the University of Ottawa in Canada and the University of Rochester in the United States. Light with Orbital Angular Momentum (owing to a twisted phase front) is traditionally generated using specially designed optical elements such as spatial light modulator, cylindrical lens mode converters and q-plate. The researchers have now shown that a plasmonic metasurface comprising an array of nano-antennas can couple spin-to-Orbital Angular Momentum at thickness much smaller than the wavelength of the light with an efficiency of around 3%. The conversion takes place due to the birefringence present in the nanostructure array. This approach could yield ultrathin generators of visible light with Orbital Angular Momentum, for potential applications in spectroscopy, imaging, sensing and quantum information.
Les Allen - One of the best experts on this subject based on the ideXlab platform.
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IV The Orbital Angular Momentum of Light
Progress in Optics, 2009Co-Authors: Les Allen, Miles J. Padgett, Mohamed BabikerAbstract:Publisher Summary This chapter discusses the Orbital Angular Momentum of light, outlines the theoretical basis for the Orbital Angular Momentum of beams within the paraxial approximation, and indicates the unapproximated theory, based on the full set of Maxwell equations. The chapter discusses the problems associated with the separation and identification of spin and Orbital contributions to the Angular Momentum properties of a field, the properties of Laguerre–Gaussian beams, which are physically realizable in the laboratory, and the ways in which the beams may be generated. It reviews the phenomenological behavior of beams possessing Orbital Angular Momentum and their interaction with matter in bulk. The chapter also describes the measurement of the rotational Doppler shift, which arises when beams possessing Orbital and spin Angular momenta are rotated. The dipole-interaction of atoms with the Orbital Angular Momentum of light beams is considered. The roles of spin and Orbital Angular Momentum are also compared and contrasted.
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light s Orbital Angular Momentum
Physics Today, 2004Co-Authors: Miles J. Padgett, Johannes Courtial, Les AllenAbstract:The realization that light beams can have quantized Orbital Angular Momentum in addition to spin Angular Momentum has led, in recent years, to novel experiments in quantum mechanics and new methods for manipulating microparticles
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two photon entanglement of Orbital Angular Momentum states
Physical Review A, 2002Co-Authors: Sonja Frankearnold, Miles J. Padgett, Stephen M. Barnett, Les AllenAbstract:We investigate the Orbital Angular Momentum correlation of a photon pair created in a spontaneous parametric down-conversion process. We show how the conservation of the Orbital Angular Momentum in this process results from phase matching in the nonlinear crystal.
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intrinsic and extrinsic nature of the Orbital Angular Momentum of a light beam
Physical Review Letters, 2002Co-Authors: Anna T Oneil, Les Allen, I Macvicar, Miles J. PadgettAbstract:We explain that, unlike the spin Angular Momentum of a light beam which is always intrinsic, the Orbital Angular Momentum may be either extrinsic or intrinsic. Numerical calculations of both spin and Orbital Angular Momentum are confirmed by means of experiments with particles trapped off axis in optical tweezers, where the size of the particle means it interacts with only a fraction of the beam profile. Orbital Angular Momentum is intrinsic only when the interaction with matter is about an axis where there is no net transverse Momentum.
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parametric down conversion for light beams possessing Orbital Angular Momentum
Physical Review A, 1999Co-Authors: Jochen Arlt, Les Allen, Kishan Dholakia, Miles J. PadgettAbstract:We investigate the spontaneous parametric down-conversion for light beams possessing Orbital Angular Momentum. The experimental results indicate that the Orbital Angular Momentum is not conserved within the classical light fields. This is in contrast to second harmonic generation where the conservation of Orbital Angular Momentum leads to a well-defined mode transformation. We attribute this difference in behavior to the loss of spatial coherence within each of the down-converted fields. [S1050-2947(99)01205-6].
Kishan Dholakia - One of the best experts on this subject based on the ideXlab platform.
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Orbital Angular Momentum transfer to optically levitated microparticles in vacuum
Physical Review A, 2016Co-Authors: Michael Mazilu, Kishan Dholakia, Yoshihiko Arita, Tom Vettenburg, Juan M Aunon, Ewan M WrightAbstract:We demonstrate the transfer of Orbital Angular Momentum to an optically levitated microparticle in vacuum. The microparticle is placed within a Laguerre-Gaussian beam and orbits the annular beam profile with increasing Angular velocity as the air drag coefficient is reduced. We explore the particle dynamics as a function of the topological charge of the levitating beam. Our results reveal that there is a fundamental limit to the Orbital Angular Momentum that may be transferred to a trapped particle, dependent upon the beam parameters and inertial forces present.
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transfer of Orbital Angular Momentum to an optically trapped low index particle
Physical Review A, 2002Co-Authors: V Garceschavez, Karen Volkesepulveda, Sabino Chavezcerda, W Sibbett, Kishan DholakiaAbstract:We demonstrate the transfer of Orbital Angular Momentum from a light beam to a trapped low-index particle. The particle is trapped in a dark annular region of a high-order Bessel beam and rotates around the beam axis due to scattering from the helical wave fronts of the light beam. A general theoretical geometrical optics model is developed that, applied to our specific situation, corroborates tweezing and transfer of Orbital Angular Momentum to the low-index particle. Good quantitative agreement between theory and experiment for particle rotation rates is observed.
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Orbital Angular Momentum of a high order bessel light beam
Journal of Optics B-quantum and Semiclassical Optics, 2002Co-Authors: Karen Volkesepulveda, V Garceschavez, Sabino Chavezcerda, Jochen Arlt, Kishan DholakiaAbstract:The Orbital Angular Momentum density of Bessel beams is calculated explicitly within a rigorous vectorial treatment. This allows us to investigate some aspects that have not been analysed previously, such as the Angular Momentum content of azimuthally and radially polarized beams. Furthermore, we demonstrate experimentally the mechanical transfer of Orbital Angular Momentum to trapped particles in optical tweezers using a high-order Bessel beam. We set transparent particles of known dimensions into rotation, where the sense of rotation can be reversed by changing the sign of the singularity. Quantitative results are obtained for rotation rates. This paper's animations are available from the Multimedia Enhancements page.
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parametric down conversion for light beams possessing Orbital Angular Momentum
Physical Review A, 1999Co-Authors: Jochen Arlt, Les Allen, Kishan Dholakia, Miles J. PadgettAbstract:We investigate the spontaneous parametric down-conversion for light beams possessing Orbital Angular Momentum. The experimental results indicate that the Orbital Angular Momentum is not conserved within the classical light fields. This is in contrast to second harmonic generation where the conservation of Orbital Angular Momentum leads to a well-defined mode transformation. We attribute this difference in behavior to the loss of spatial coherence within each of the down-converted fields. [S1050-2947(99)01205-6].
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mechanical equivalence of spin and Orbital Angular Momentum of light an optical spanner
Optics Letters, 1997Co-Authors: N B Simpson, Les Allen, Kishan Dholakia, Miles J. PadgettAbstract:We use a Laguerre–Gaussian laser mode within an optical tweezers arrangement to demonstrate the transfer of the Orbital Angular Momentum of a laser mode to a trapped particle. The particle is optically confined in three dimensions and can be made to rotate; thus the apparatus is an optical spanner. We show that the spin Angular Momentum of ±ℏ per photon associated with circularly polarized light can add to, or subtract from, the Orbital Angular Momentum to give a total Angular Momentum. The observed cancellation of the spin and Orbital Angular Momentum shows that, as predicted, a Laguerre–Gaussian mode with an azimuthal mode index l=1 has a well-defined Orbital Angular Momentum corresponding to ℏ per photon.
Mohamed Babiker - One of the best experts on this subject based on the ideXlab platform.
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electron vortices beams with Orbital Angular Momentum
Reviews of Modern Physics, 2017Co-Authors: Sophia Marriott Lloyd, Mohamed Babiker, Gnanavel Thirunavukkarasu, Jun YuanAbstract:This article presents a review on electron vortex beams highlighting both its experimental and its theoretical aspects. The unique characteristics of electron vortex states as well as their similarities with Orbital Angular Momentum states of light are discussed and perspectives are offered for their application in a number of technologies.
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electron vortices beams with Orbital Angular Momentum
Reviews of Modern Physics, 2017Co-Authors: Sophia Marriott Lloyd, Mohamed Babiker, Gnanavel Thirunavukkarasu, Jun YuanAbstract:The recent prediction and subsequent creation of electron vortex beams in a number of laboratories occurred after almost 20 years had elapsed since the recognition of the physical significance and potential for applications of the Orbital Angular Momentum carried by optical vortex beams. A rapid growth in interest in electron vortex beams followed, with swift theoretical and experimental developments. Much of the rapid progress can be attributed in part to the clear similarities between electron optics and photonics arising from the functional equivalence between the Helmholtz equations governing the free-space propagation of optical beams and the time-independent Schrodinger equation governing freely propagating electron vortex beams. There are, however, key differences in the properties of the two kinds of vortex beams. This review is primarily concerned with the electron type, with specific emphasis on the distinguishing vortex features: notably the spin, electric charge, current and magnetic moment, the spatial distribution, and the associated electric and magnetic fields. The physical consequences and potential applications of such properties are pointed out and analyzed, including nanoparticle manipulation and the mechanisms of Orbital Angular Momentum transfer in the electron vortex interaction with matter.
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IV The Orbital Angular Momentum of Light
Progress in Optics, 2009Co-Authors: Les Allen, Miles J. Padgett, Mohamed BabikerAbstract:Publisher Summary This chapter discusses the Orbital Angular Momentum of light, outlines the theoretical basis for the Orbital Angular Momentum of beams within the paraxial approximation, and indicates the unapproximated theory, based on the full set of Maxwell equations. The chapter discusses the problems associated with the separation and identification of spin and Orbital contributions to the Angular Momentum properties of a field, the properties of Laguerre–Gaussian beams, which are physically realizable in the laboratory, and the ways in which the beams may be generated. It reviews the phenomenological behavior of beams possessing Orbital Angular Momentum and their interaction with matter in bulk. The chapter also describes the measurement of the rotational Doppler shift, which arises when beams possessing Orbital and spin Angular momenta are rotated. The dipole-interaction of atoms with the Orbital Angular Momentum of light beams is considered. The roles of spin and Orbital Angular Momentum are also compared and contrasted.
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Orbital Angular Momentum exchange in the interaction of twisted light with molecules
Physical Review Letters, 2002Co-Authors: Mohamed Babiker, C R Bennett, David L Andrews, L Davila C RomeroAbstract:In the interaction of molecules with light endowed with Orbital Angular Momentum, an exchange of Orbital Angular Momentum in an electric dipole transition occurs only between the light and the center of mass motion; i.e., internal i?½electronic-typei?½ motion does not participate in any exchange of Orbital Angular Momentum in a dipole transition. A quadrupole transition is the lowest electric multipolar process in which an exchange of Orbital Angular Momentum can occur between the light, the internal motion, and the center of mass motion. This rules out experiments seeking to observe exchange of Orbital Angular Momentum between light beams and the internal motion in electric dipole transitions.
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atomic motion in light beams possessing Orbital Angular Momentum
Physical Review A, 1995Co-Authors: William Power, Les Allen, Mohamed Babiker, V E LembessisAbstract:A theory is developed that leads to the description of the internal and gross motions of an atom interacting with an arbitrary light field. The general results are then applied to the case of a Laguerre-Gaussian (LG) mode, one of a class of modes of electromagnetic radiation that possess Orbital Angular Momentum. A number of effects are predicted, notably, an azimuthal shift in the atomic resonance, a modified radiation pressure force, and an associated torque on the atom. It is pointed out that the effects originate in the processes of the transfer of linear and Orbital Angular Momentum from the field to the atomic gross motion. The strengths of the effects are assessed in relation to the normal axial Doppler shift and the linear light pressure force. The motion of atoms and ions subject to the LG pressure force is studied by solving the classical equation of motion. Trajectories clearly exhibiting the effects of Orbital Angular Momentum are displayed for a free atom and for an ion in a two-dimensional trap and in a Paul trap.
