Maximizing quantum discord from interference in multi-port fiber beamsplitters

AbstractFourth-order interference is an information processing primitive for photonic quantum technologies, as it forms the basis of photonic controlled-logic gates, entangling measurements, and can be used to produce quantum correlations. Here, using classical weak coherent states as inputs, we study fourth-order interference in 4 × 4 multi-port beam splitters built within multi-core optical fibers, and show that quantum correlations, in the form of geometric quantum discord, can be controlled and maximized by adjusting the intensity ratio between the two inputs. Though these states are separable, they maximize the geometric discord in some instances, and can be a resource for protocols such as remote state preparation. This should contribute to the exploitation of quantum correlations in future telecommunication networks, in particular in those that exploit spatially structured fibers.

Download Full-text

Improvement of quantum correlations by repetitive quantum error correction

International Journal of Quantum Information ◽

10.1142/s0219749919500448 ◽

2019 ◽

Vol 17 (05) ◽

pp. 1950044

Author(s):

A. El Allati ◽

H. Amellal ◽

A. Meslouhi

Keyword(s):

Error Correction ◽

Quantum Correlation ◽

Coherent States ◽

Quantum Discord ◽

Error Correcting Code ◽

Quantum Correlations ◽

Quantum Error Correction ◽

Optical Field ◽

Quantum Error ◽

Entangled Coherent States

A quantum error-correcting code is established in entangled coherent states (CSs) with Markovian and non-Markovian environments. However, the dynamic behavior of these optical states is discussed in terms of quantum correlation measurements, entanglement and discord. By using the correcting codes, these correlations can be as robust as possible against environmental effects. As the number of redundant CSs increases due to the repetitive error correction, the probabilities of success also increase significantly. Based on different optical field parameters, the discord can withstand more than an entanglement. Furthermore, the behavior of quantum discord under decoherence may exhibit sudden death and sudden birth phenomena as functions of dimensionless parameters.

Download Full-text

Quantum Discord in Photon-Added Glauber Coherent States of GHZ-Type

Open Systems & Information Dynamics ◽

10.1142/s1230161215500237 ◽

2015 ◽

Vol 22 (04) ◽

pp. 1550023

Author(s):

M. Daoud ◽

W. Kaydi ◽

H. El Hadfi

Keyword(s):

Coherent States ◽

Quantum Discord ◽

Quantum Correlations ◽

Photon Excitation ◽

Pairwise Correlations ◽

Photon Excitations

We investigate the influence of photon excitations on quantum correlations in tripartite Glauber coherent states of Greenberger-Horne-Zeilinger type (GHZ-type). The pairwise correlations are measured by means of the entropy-based quantum discord. We also analyze the monogamy property of quantum discord in this class of tripartite states in terms of the strength of Glauber coherent states and the photon excitation order.

Download Full-text

Thermal quantum correlations in a two-qubit Heisenberg XYZ model with different magnetic fields

International Journal of Quantum Information ◽

10.1142/s021974991550046x ◽

2015 ◽

Vol 13 (06) ◽

pp. 1550046 ◽

Cited By ~ 1

Author(s):

Zheng Hu ◽

Yu-Chen Wang ◽

Xi-Wen Hou

Keyword(s):

Magnetic Field ◽

Information Processing ◽

Quantum Information ◽

Magnetic Fields ◽

Finite Temperature ◽

Quantum Discord ◽

Quantum Information Processing ◽

Quantum Correlations ◽

Field Coupling ◽

Magnetic Field Coupling

Two kinds of thermal quantum correlations, measured respectively by quantum discord (QD) and the generalized negativity (GN), are studied for various magnetic fields, couplings, and temperatures in a two-qubit Heisenberg XYZ model. It is shown that QD and GN can exhibit a similar behavior in some regions of magnetic field, coupling, and temperature, while they behave in a contrary manner in other regions. For example, QD may increase with suitable magnetic fields, couplings, and temperature when GN decreases. QD is more robust against temperature than GN, and can reveal a kink at a suitable coupling at finite temperature while GN cannot. Moreover, a nearly unchanged QD or GN can be obtained in a large region of magnetic field, coupling, and temperature. These adjustable QD and GN via the varied magnetic field, coupling, and temperature may have significant applications in quantum information processing.

Download Full-text

Distribution of geometric quantum discord in photon-added coherent states

Modern Physics Letters B ◽

10.1142/s0217984915502395 ◽

2015 ◽

Vol 29 (35n36) ◽

pp. 1550239 ◽

Cited By ~ 1

Author(s):

M. Daoud ◽

W. Kaydi ◽

H. El Hadfi

Keyword(s):

Coherent States ◽

Quantum Discord ◽

Quantum Correlations ◽

Geometric Quantum Discord ◽

Photon Excitation ◽

Schmidt Norm

In this paper, we examine the influence of photon excitation on the monogamy property of quantum discord in tripartite coherent states of Greenberger–Horne–Zeilinger (GHZ) type. The Hilbert–Schmidt norm is used as quantifier of pairwise quantum correlations. The geometric quantum discord in all bipartite subsystems are explicitly given. We show that the geometric discord is monogamous for any photon excitation order.

Download Full-text

QUANTUM CORRELATIONS DYNAMICS OF QUASI-BELL CAT STATES

International Journal of Quantum Information ◽

10.1142/s0219749913500573 ◽

2013 ◽

Vol 11 (06) ◽

pp. 1350057 ◽

Cited By ~ 1

Author(s):

M. DAOUD ◽

R. AHL LAAMARA ◽

R. ESSABER

Keyword(s):

Coherent States ◽

Quantum Discord ◽

Quantum Correlations ◽

Geometric Quantum Discord ◽

Entanglement Of Formation ◽

Analytic Expressions ◽

Cat States

A model of dynamics of quantum correlations of two modes quasi-Bell cat states, based on Glauber coherent states, is considered. The analytic expressions of pairwise entanglement of formation, quantum discord and its geometrized variant are explicitly derived. We analyze the distribution of quantum correlations between the two modes and the environment. We show that, in contrast with squared concurrence, entanglement of formation, quantum discord and geometric quantum discord do not follow the property of monogamy except in some particular situations that we discuss.

Download Full-text

Entanglement of formation and quantum discord in multipartite j-spin coherent states

International Journal of Modern Physics B ◽

10.1142/s0217979220502379 ◽

2020 ◽

Vol 34 (26) ◽

pp. 2050237

Author(s):

H. Baba ◽

W. Kaydi ◽

M. Daoud ◽

M. Mansour

Keyword(s):

Coherent States ◽

Quantum Discord ◽

Quantum Correlations ◽

Quantum Systems ◽

Spin Coherent State ◽

Entanglement Of Formation ◽

Multipartite System ◽

Single Formula ◽

Qubit States ◽

Spin Coherent States

We study the entanglement of formation and the quantum discord contained in even and odd multipartite [Formula: see text]-spin coherent states. The key element of this investigation is the fact that a single [Formula: see text]-spin coherent state is viewed as comprising [Formula: see text] qubit states. We compute the quantum correlations present in the n even and odd [Formula: see text]-spin coherent states by considering all possible bipartite splits of the multipartite system. We discuss the different bi-partition schemes of quantum systems and we examine in detail the conservation rules governing the distribution of quantum correlations between the different qubits of the multipartite system. Finally, we derive the explicit expressions of quantum correlations present in even and odd spin coherent states decomposed in four spin sub-systems. We also analyze the properties of monogamy and we show in particular that the entanglement of the formation and the quantum discord obey the relation of monogamy only for even multipartite [Formula: see text]-spin coherent states.

Download Full-text

QUANTUM DISCORD FOR MULTIPARTITE COHERENT STATES INTERPOLATING BETWEEN WERNER AND GREENBERGER–HORNE–ZEILINGER STATES

International Journal of Quantum Information ◽

10.1142/s0219749912500608 ◽

2012 ◽

Vol 10 (05) ◽

pp. 1250060 ◽

Cited By ~ 19

Author(s):

M. DAOUD ◽

R. AHL LAAMARA

Keyword(s):

Quantum System ◽

Ground State ◽

Coherent States ◽

Quantum Discord ◽

Temporal Evolution ◽

Conditional Entropy ◽

Quantum Correlations ◽

Ghz States ◽

Werner States ◽

Explicit Expressions

The quantum discord is used as measure of quantum correlations for two families of multipartite coherent states. The first family interpolates between generalized GHZ states and generalized Werner states. The second one is an interpolation between generalized GHZ and the ground state of the multipartite quantum system. Two inequivalent ways to split the system in a pair of qubits are introduced. The explicit expressions of quantum quantum discord in multipartite coherent states are derived. Its evaluation uses the Koashi–Winter relation in optimizing the conditional entropy. The temporal evolution of quantum correlations (quantum discord and entanglement) is also discussed.

Download Full-text