Levels of Quantum Correlations in the Continuous Variable Regime: Review and Experimental Illustrations with OPOs

2009 ◽  
Author(s):  
V. D’Auria ◽  
G. Keller ◽  
J. Laurat ◽  
N. Treps ◽  
T. Amri ◽  
...  
Keyword(s):  
Quantum Correlations ◽  
Continuous Variable ◽  
Variable Regime

scholarly journals Fidelity-based unitary operation-induced quantum correlation for continuous-variable systems

2019 ◽  
Vol 17 (04) ◽  
pp. 1950035
Author(s):  
Liang Liu ◽  
Xiaofei Qi ◽  
Jinchuan Hou
Keyword(s):  
Quantum Correlation ◽  
Quantum Correlations ◽  
Continuous Variable ◽  
Gaussian Channel ◽  
Simple Computation ◽  
Gaussian States ◽  
Text Mode ◽  
Computation Formula ◽  
Geometric Measurement ◽  
Thermal States

We propose a measure of nonclassical correlation [Formula: see text] in terms of local Gaussian unitary operations based on square of the fidelity [Formula: see text] for bipartite continuous-variable systems. This quantity is easier to be calculated or estimated and is a remedy for the local ancilla problem associated with the geometric measurement-induced nonlocality. A simple computation formula of [Formula: see text] for any [Formula: see text]-mode Gaussian states is presented and an estimation of [Formula: see text] for any [Formula: see text]-mode Gaussian states is given. For any [Formula: see text]-mode Gaussian states, [Formula: see text] does not increase after performing a local Gaussian channel on the unmeasured subsystem. Comparing [Formula: see text] in scale with other quantum correlations such as Gaussian geometric discord for two-mode symmetric squeezed thermal states reveals that [Formula: see text] is much better in detecting quantum correlations of Gaussian states.

scholarly journals On Amplification of Light in the Continuous EPR State

2003 ◽  
Vol 01 (02) ◽  
pp. 207-215 ◽  
Author(s):  
V. N. Gorbachev ◽  
A. I. Trubilko
Keyword(s):  
Quantum Correlations ◽  
Continuous Variable ◽  
The Other ◽  
Atomic Ensemble ◽  
Transparent Medium ◽  
Integrals Of Motion ◽  
Squeezed Light ◽  
Type Interaction ◽  
Epr State

Two schemes of amplification of two-mode squeezed light in the continuous variable EPR-state are considered. They are based on the integrals of motion, which allow conserving quantum correlations whereas the power of each mode may increase. One of these schemes involves a three-photon parametric process in a nonlinear transparent medium and the other is a Raman type interaction of light with atomic ensemble. A generalization to multimode squeezed light is discussed.

scholarly journals THE BALANCE OF QUANTUM CORRELATIONS FOR A CLASS OF FEASIBLE TRIPARTITE CONTINUOUS VARIABLE STATES

2012 ◽  
Vol 27 (01n03) ◽  
pp. 1345024 ◽  
Author(s):  
STEFANO OLIVARES ◽  
MATTEO G. A. PARIS
Keyword(s):  
Conservation Laws ◽  
Quantum Discord ◽  
Quantum Correlations ◽  
Continuous Variable ◽  
Noisy Environment ◽  
Mixed States ◽  
Von Neumann ◽  
Entanglement Of Formation ◽  
Pure States ◽  
Gaussian Quantum Discord

We address the balance of quantum correlations for continuous variable (CV) states. In particular, we consider a class of feasible tripartite CV pure states and explicitly prove two Koashi–Winter-like conservation laws involving Gaussian entanglement of formation (EoF), Gaussian quantum discord and sub-system Von Neumann entropies. We also address the class of tripartite CV mixed states resulting from the propagation in a noisy environment, and discuss how the previous equalities evolve into inequalities.

ALL-FIBRE SOURCE OF CONTINUOUS VARIABLE ENTANGLED LIGHT

2006 ◽  
Vol 20 (11n13) ◽  
pp. 1280-1286 ◽  
Author(s):  
A. NANDAN ◽  
M. SABUNCU ◽  
J. HEERSINK ◽  
O. GLÖCKL ◽  
G. LEUCHS ◽  
...  
Keyword(s):  
Kerr Effect ◽  
Beam Splitter ◽  
Laser Pulses ◽  
Quantum Correlations ◽  
Continuous Variable ◽  
Sagnac Interferometer ◽  
Detection Scheme ◽  
Fully Integrated ◽  
Simple Detection

We experimentally demonstrate the production of continuous variable entanglement of femto second laser pulses from an all-fibre asymmetric Sagnac interferometer exploiting the Kerr effect. Contrary to the experiment of Silberhorn et al. [Phys. Rev. Lett. 86, 4267 (2001)], the asymmetric coupler in the Sagnac loop is fully integrated in the fibre, making the source extremely compact, reliable and robust. Employing a simple detection scheme, comprising a beam splitter and two intensity detectors, we clearly observe quantum correlations of conjugate quadratures, hereby witnessing entanglement.

scholarly journals ENTANGLEMENT SHARING: FROM QUBITS TO GAUSSIAN STATES

2006 ◽  
Vol 04 (03) ◽  
pp. 383-393 ◽  
Author(s):  
GERARDO ADESSO ◽  
FABRIZIO ILLUMINATI
Keyword(s):  
Information Theory ◽  
Quantum Information ◽  
Quantum Correlations ◽  
Quantum Information Theory ◽  
Continuous Variable ◽  
Quantum Systems ◽  
Tripartite Entanglement ◽  
Gaussian States ◽  
Trade Off ◽  
Entanglement Sharing

It is a central trait of quantum information theory that there exist limitations to the free sharing of quantum correlations among multiple parties. Such monogamy constraints have been introduced in a landmark paper by Coffman, Kundu and Wootters, who derived a quantitative inequality expressing a trade-off between the couplewise and the genuine tripartite entanglement for states of three qubits. Since then, a lot of efforts have been devoted to the investigation of distributed entanglement in multipartite quantum systems. In this paper we report, in a unifying framework, a bird's eye view of the most relevant results that have been established so far on entanglement sharing in quantum systems. We will take off from the domain of N qubits, graze qudits, and finally land in the almost unexplored territory of multimode Gaussian states of continuous variable systems.

Quantum correlations for bipartite continuous-variable systems

2018 ◽  
Vol 17 (4) ◽  
Author(s):  
Ruifen Ma ◽  
Jinchuan Hou ◽  
Xiaofei Qi ◽  
Yangyang Wang
Keyword(s):  
Quantum Correlations ◽  
Continuous Variable
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