42 research outputs found
Wigner distribution of twisted photons
We present the first experimental characterization of the azimuthal Wigner
distribution of a photon. Our protocol fully characterizes the transverse
structure of a photon in conjugate bases of orbital angular momentum (OAM) and
azimuthal angle (ANG). We provide a test of our protocol by characterizing pure
superpositions and incoherent mixtures of OAM modes in a seven-dimensional
space. The time required for performing measurements in our scheme scales only
linearly with the dimension size of the state under investigation. This time
scaling makes our technique suitable for quantum information applications
involving a large number of OAM states
Multiplexing Free-Space Channels using Twisted Light
We experimentally demonstrate an interferometric protocol for multiplexing
optical states of light, with potential to become a standard element in
free-space communication schemes that utilize light endowed with orbital
angular momentum (OAM). We demonstrate multiplexing for odd and even OAM
superpositions generated using different sources. In addition, our technique
permits one to prepare either coherent superpositions or statistical mixtures
of OAM states. We employ state tomography to study the performance of this
protocol, and we demonstrate fidelities greater than 0.98.Comment: 4 pages, 3 figure
Rapid Generation of Light Beams Carrying Orbital Angular Momentum
We report a technique for encoding both amplitude and phase variations onto a
laser beam using a single digital micro-mirror device (DMD). Using this
technique, we generate Laguerre-Gaussian and vortex orbital-angular-momentum
(OAM) modes, along with modes in a set that is mutually unbiased with respect
to the OAM basis. Additionally, we have demonstrated rapid switching among the
generated modes at a speed of 4 kHz, which is much faster than the speed
regularly achieved by spatial light modulators (SLMs). The dynamic control of
both phase and amplitude of a laser beam is an enabling technology for
classical communication and quantum key distribution (QKD) systems that employ
spatial mode encoding