Open AccessGeneration of two pairs of qudits using four photons and a single degree of freedom
Author(s) -
Pierre-Louis de Assis,
M. A. D. Carvalho,
L. P. Berruezo,
J. Ferraz,
S. Pádua
Publication year - 2016
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.030149
Subject(s) - quantum entanglement , physics , separable state , qubit , photon , quantum mechanics , quantum state , degree (music) , quantum , quantum information , state (computer science) , degrees of freedom (physics and chemistry) , computer science , quantum discord , algorithm , acoustics
Qudits, d-level quantum systems, have been shown to provide a better resource for quantum key distribution and other Quantum Information protocols. It is customary to generate photonic qudits using more than one degree of freedom of the same photon. In much the same way, multi-qubit states are generated using only a pair of photons and ingenious ways to manipulate more than one degree of freedom independently. In contrast to such costly implementations in terms of quantum resources, we present the controlled generation of two copies of two-qudit states using four photons and a single degree of freedom, transverse momentum. The degree of entanglement within each pair was inferred by exploiting the availability of two copies of the same state, without the need of a full tomographic reconstruction of the states, and both highly-entangled and separable states were generated. We show theoretically that the set of states obtainable using our setup is very diverse, ranging from maximally entangled states of qudits to separable states.