Ali Anwar
Physical Research Laboratory
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Publication
Featured researches published by Ali Anwar.
Applied Optics | 2015
Salla Gangi Reddy; Chithrabhanu Permangatt; Shashi Prabhakar; Ali Anwar; J. Banerji; R. P. Singh
We show, both theoretically and experimentally, that the propagation of optical vortices in free space can be analyzed by using the width [w(z)] of the host Gaussian beam and the inner and outer radii of the vortex beam at the source plane (z=0) as defined in [Opt. Lett.39, 4364 (2014)10.1364/OL.39.004364OPLEDP0146-9592]. We also studied the divergence of vortex beams, considered as the rate of change of inner or outer radius with the propagation distance (z), and found that it varies with the order in the same way as that of the inner and outer radii at z=0. These results may be useful in designing optical fibers for orbital angular momentum modes that play a crucial role in quantum communication.
Applied Physics Letters | 2015
Gangi Reddy Salla; Chithrabhanu Perumangattu; Shashi Prabhakar; Ali Anwar; R. P. Singh
We generate optical vortices and scatter them through a rough surface. However, the scattered light passing through a lens shows the same vorticity when probed at the Fourier plane. The vorticity is measured using a nonseparable state of polarization and orbital angular momentum of light as it cannot be confirmed by the standard interferometric technique. The observed vorticity is found to be independent of the amount of scattered light collected. Therefore, vortices can be used as information carriers even in the presence of scattering media. The experimental results are well supported by the theoretical results.
International Conference on Optics and Photonics 2015 | 2015
Chithrabhanu P; Salla Gangi Reddy; Ali Anwar; R. P. Singh
We construct a orbital angular momentum (OAM) Poincar´e sphere in which we can represent 2-D superposition states of arbitrary OAM. In addition, we represent the mixed states of OAM as non separable states inside the sphere. We also give an experimental set up to generate all points on this sphere.
Physics Letters A | 2017
Chithrabhanu Perumangatt; Nijil Lal; Ali Anwar; Salla Gangi Reddy; R. P. Singh
Abstract We address the possibility of using even/odd states of orbital angular momentum (OAM) of photons for the quantum information tasks. Single photon qubit states and two photon entangled states in even/odd basis of OAM are considered. We present a method for the tomography and general projective measurement in even/odd basis. With the general projective measurement, we show the Bell violation and quantum cryptography with Bells inequality. We also describe hyper and hybrid entanglement of even/odd OAM states along with polarization, which can be applied in the implementation of quantum protocols like super dense coding.
Journal of The Optical Society of America B-optical Physics | 2016
Chithrabhanu P; Salla Gangi Reddy; Nijil Lal; Ali Anwar; A. Aadhi; R. P. Singh
We generate the non-separable state of polarization and orbital angular momentum (OAM) using a laser beam. The generated state undergoes a cyclic polarization evolution which introduces a Pancharatnam geometric phase to the polarization state and in turn a relative phase in the non-separable state. We experimentally study the violation of Bell - CHSH inequality for different Pancharatnam phases introduced by various cyclic polarization evolutions with linear and circular states as measurement bases. While measuring in linear bases, the Bell-CHSH parameter oscillates with Pancharatnam phase. One can overcome this dependence by introducing a relative phase in one of the projecting state. However for measurement in circular bases, the Pancharatnam phase does not affect the Bell-CHSH violation.
2015 Workshop on Recent Advances in Photonics (WRAP) | 2015
Ali Anwar; Nijil Lal; Chithrabhanu P; Gangi Reddy Salla; R. P. Singh; Shashi Prabhakar
We investigate the methods to obtain maximum correlated photon pairs generated in Type I spontaneous parametric down conversion (SPDC) with focused pump beam. We study the effect of pump focusing on the photon collection efficiency of signal and idler modes. The correlated photon pair collection efficiency decreases asymptotically with input pump beam focusing parameter [1]. The results obtained here are expected to be useful in designing appropriate optical fibers for generating efficient entangled photon sources for quantum information applications.
Optics Communications | 2015
Chithrabhanu Perumangatt; Gangi Reddy Salla; Ali Anwar; A. Aadhi; Shashi Prabhakar; R. P. Singh
arXiv: Quantum Physics | 2018
M. V. Jabir; Ali Anwar; G.K. Samanta
Optics Letters | 2018
Ali Anwar; Pravin Vaity; Chithrabhanu Perumangatt; R. P. Singh
Journal of Optics | 2018
Vijay Kumar; Ali Anwar; R. P. Singh