Experimental characterization of continuous-variable orbital angular momentum entanglement using Stokes-operator basis

The continuous-variable (CV) orbital angular momentum (OAM) entanglement is very different to the traditional quadrature entanglement. The Stokes-operators directly reflect the character of OAM light. Here, we report the first direct experimental demonstration the Stokes-operator entanglement of continuous-variable OAM entanglement. Generated by transforming quadrature entanglement in the HG(01) mode onto the orbital Stokes-operator basis, the entanglement is measured in the Stokes-operator basis using a self-designed detection scheme. An inseparability of I((O) over cap (2), (O) over cap (3)) < 1 is achieved over a wide analyzing frequency of 1-10 MHz. Moreover, experimental fluctuations at 5.0 MHz are visualized using the quantum orbital Poincare sphere representation. The OAM entanglement with Stokes-operators measurement has a promising application in certain nonlocal quantum information protocols and rotational optomechanics by interacting with nanoparticle or atoms. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement