arXiv subjects

Daniel Balado

Publications and source records attributed to Daniel Balado.

3 recordsLinked to original sources

arXiv2021

Quantum projectors implemented with optical directional couplers fabricated by Na/K ion-exchange in soda-lime glass

We present a preliminary theoretical and experimental study of quantum projectors implemented by integrated optical directional couplers fabricated by ion-exchange Na/K processes in soda-lime glass. Theoretical considerations about devices formed by concatenated 2x2 directional couplers are presented in order to show their capabilities for implementing N-dimensional quantum projective measurements, and concomitantly the production of 1-qudit states. Since the fundamental unit of these devices are 2x2 directional couplers, we present an experimental study for obtaining, by an optical characterization, empiric relationships between fabrication and optical parameters of such couplers. Likewise, a two-dimensional quantum projector is demonstrated in such a way that projective measurements are obtained for the states of X (diagonal) and Y (circular) bases.

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arXiv2020

Fully autocompensating high-dimensional quantum cryptography by optical phase conjugation

We present a bidirectional quantum communication system based on optical phase conjugation for achieving fully autocompensating high-dimensional quantum cryptography. We prove that random phase shifts and couplings among 2N spatial and polarization optical modes described by SU(2N) transformations due to perturbations are autocompensated after a single round trip between Alice and Bob. Bob can use a source of single photons or, alternatively, coherent states and then Alice attenuates them up to a single photon level, and thus non-perturbated 1-qudit states are generated for high-dimensional QKD protocols, as the BB84 one, of a higher security.

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arXiv2020

Engineering continuous and discrete variable quantum vortex states by nonlocal photon subtraction in a reconfigurable photonic chip

We study the production of entangled two- and N-mode quantum states of light in optical waveguides. To this end, we propose a quantum photonic circuit that produces a reconfigurable superposition of photon subtraction on two single-mode squeezed states. Under postselection, continuous variable or discrete variable entangled states with possibilities in quantum information processing are obtained. Likewise, nesting leads to higher-dimension entanglement with a similar design, enabling the generation of non-Gaussian continuous variable cluster states. Additionally, we show the operation of the device through the generation of quantum vortex states of light and propose an integrated device that measures their order and handedness. Finally, we study the non-Gaussianity, nonclassicality, and entanglement of the quantum states generated with this scheme by means of the optical field-strength distribution, Wigner function, and logarithmic negativity.

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