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Physical Review A

Spin-orbit X states

W. F. Balthazar, D. G. Braga, V. S. Lamego, M. H. M. Passos, J. A. O. Huguenin

Published Feb 10, 2021• 16 citations
Publisher

Abstract

We propose an all-optical setup to produce a wide class of $X$ states with an intense laser beam using spin-orbit modes. In order to characterize such simulated states, we reconstructed the density matrix by simulating spin-orbit tomography and studied the discord and concurrence for different states. The results show very good agreement with theoretical predictions. We also propose two different optical circuits to prepare the single-photon spin-orbit $X$ state.

DOI
10.1103/physreva.103.022411

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We propose an all-optical setup to produce a wide class of XXX states with an intense laser beam using spin-orbit modes. In order to characterize such simulated states, we reconstructed the density matrix by simulating spin-orbit tomography and studied the discord and concurrence for different states. The results show very good agreement with theoretical predictions. We also propose two different optical circuits to prepare the single-photon spin-orbit XXX state.
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We perform an experimental investigation of Quantum Discord with Spin-Orbit X-states. These states are prepared through the incoherent superposition of different laser beans, where a two-level system is encoded in polarization and the first-order Hermitian-Gaussian modes, as proposed in Phys. Rev. A 103,0022411 (2022). We characterize different classes of spin-orbit X-states by performing an all-optical tomography for polarization and first-order transverse mode degrees of freedom. We also perform a study on the dependence of Discord with respect to the Fidelity of spin-orbit modes, revealing that Discord is very sensitive to incoherent noise. Our experimental results align with the theoretical predictions of Quantum Discord when accounting for the effect of fidelity. These results reinforce the spin-orbit modes as an important platform for quantum information processing. On the other hand, the need of astigmatic optical elements to implement unitary operations required by quantum information protocols implies in a loss of fidelity and quantum correlations. Alternative methods to manipulate spin-orbit modes are welcome.
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We introduce a proposal to prepare spin-obit maximally discordant mixed states by a linear optical circuit, with quantum bits (qubits) encoded in the polarization and transverse mode degrees of freedom of photons. In particular, we discuss how to prepare nonbalanced spin-orbit entangled states, applying this technique to obtain maximally discordant mixed states. We present a simulation of the optical circuit by using the Jones matrix formalism. We performed a study of entanglement, classical, and quantum correlations. The results show excellent agreement with the underlying theory and open an alternative experimental approach for addressing quantum correlations in optical setups.