scholarly journals Minimal disturbance measurement for coherent states is non-Gaussian

2006 ◽  
Vol 73 (3) ◽  
Author(s):  
Ladislav Mišta
Keyword(s):  
Coherent States ◽  
Non Gaussian

scholarly journals Entanglement in massive coupled oscillators

2011 ◽  
Vol 11 (3&4) ◽  
pp. 278-299
Author(s):  
Nathan L. Harshman ◽  
William F. Flynn
Keyword(s):  
Coupled Oscillators ◽  
Coherent States ◽  
Degrees Of Freedom ◽  
Classical Model ◽  
Reduced Density Matrix ◽  
One Dimension ◽  
Atomic Position ◽  
Pure States ◽  
Non Gaussian ◽  
Reduced Density

This article investigates entanglement of the motional states of massive coupled oscillators. The specific realization of an idealized diatomic molecule in one-dimension is considered, but the techniques developed apply to any massive particles with two degrees of freedom and a quadratic Hamiltonian. We present two methods, one analytic and one approximate, to calculate the interatomic entanglement for Gaussian and non-Gaussian pure states as measured by the purity of the reduced density matrix. The cases of free and trapped molecules and hetero- and homonuclear molecules are treated. In general, when the trap frequency and the molecular frequency are very different, and when the atomic masses are equal, the atoms are highly-entangled for molecular coherent states and number states. Surprisingly, while the interatomic entanglement can be quite large even for molecular coherent states, the covariance of atomic position and momentum observables can be entirely explained by a classical model with appropriately chosen statistical uncertainty.

Teleportation improvement by noiseless linear amplification

2019 ◽  
Vol 19 (11&12) ◽  
pp. 935-951
Author(s):  
Hamza Adnane ◽  
Matteo G.A. Paris
Keyword(s):  
Coherent States ◽  
Large Range ◽  
Low Energy ◽  
Entangled State ◽  
Continuous Variables ◽  
Linear Amplification ◽  
Gaussian States ◽  
Linear Amplifier ◽  
Twin Beam ◽  
Non Gaussian

We address de-Gaussification of continuous variables Gaussian states by optimal non-deterministic noiseless linear amplifier (NLA) and analyze in details the properties of the amplified states. In particular, we investigate the entanglement content and the non-Gaussian character for the class of non-Gaussian entangled state obtained by using NL-amplification of two-mode squeezed vacua (twin-beam, TWB). We show that entanglement always increases, whereas improved EPR correlations are observed only when the input TWB has low energy. We then examine a Braunstein-Kimble-like protocol for the teleportation of coherent states, and compare the performances of TWB-based teleprotation with those obtained using NL-amplified resources. We show that teleportation fidelity and security may be improved for a large range of NLA parameters (gain and threshold).

WIGNER FUNCTION EVOLUTION OF EXCITED EVEN AND ODD COHERENT STATE IN THERMAL ENVIRONMENT VIA THERMO ENTANGLED APPROACH

2013 ◽  
Vol 27 (23) ◽  
pp. 1350120 ◽  
Author(s):  
HONG-CHUN YUAN ◽  
YE-JUN XU ◽  
LEI CHEN ◽  
XUE-FEN XU
Keyword(s):  
Coherent State ◽  
Wigner Function ◽  
Decay Time ◽  
Arbitrary Number ◽  
Coherent States ◽  
Density Operator ◽  
Thermal Environment ◽  
New Approach ◽  
Non Gaussian ◽  
Analytical Expressions

We adopt a new approach, thermo entangled representation, to study time evolution of density operator in thermal environment. We then investigate the analytical expressions of Wigner function (WF) evolution of arbitrary number excited coherent states (ECSs) and excited even (odd) coherent states (EECSs, EOCSs) in thermal environment, respectively. In addition, their nonclassicality is numerically discussed by exploring the negativity of WF with decay time in thermal channel, respectively. It is found that WF loses its non-Gaussian nature and becomes Gaussian after long times.

POLARIZATION ENTANGLEMENT THROUGH NOISE

2008 ◽  
Vol 06 (supp01) ◽  
pp. 589-595 ◽  
Author(s):  
F. BENATTI ◽  
R. FLOREANINI ◽  
P. ROSINI
Keyword(s):  
Gaussian Noise ◽  
Coherent States ◽  
Two Photon ◽  
Non Gaussian

We show that a suitably engineered external non-Gaussian noise can entangle a class of initially separable, polarized two-photon coherent states.

scholarly journals EXPERIMENTAL QUANTIFICATION OF NON-GAUSSIANITY OF PHASE-RANDOMIZED COHERENT STATES

2012 ◽  
Vol 10 (08) ◽  
pp. 1241006 ◽  
Author(s):  
ALESSIA ALLEVI ◽  
STEFANO OLIVARES ◽  
MARIA BONDANI
Keyword(s):  
Experimental Investigation ◽  
Wigner Function ◽  
Coherent States ◽  
The Other ◽  
Fock States ◽  
Two Measures ◽  
Non Gaussian

We present the experimental investigation of the non-Gaussian nature of some mixtures of Fock states by reconstructing their Wigner function and exploiting two recently introduced measures of non-Gaussianity. In particular, we demonstrate the consistency between the different approaches and the monotonicity of the two measures for states belonging to the class of phase-randomized coherent states. Moreover, we prove that the exact behavior of one measure with respect to the other depends on the states under investigation and devise possible criteria to discriminate which measure is more useful for the characterization of the states in realistic applications.

scholarly journals Non-Gaussianity of Four-Photon Superpositions of Fock States

2021 ◽  
Vol 3 (3) ◽  
pp. 350-365
Author(s):  
Miguel Citeli de Freitas ◽  
Viktor V. Dodonov
Keyword(s):  
Fourth Order ◽  
Effective Temperature ◽  
Coherent States ◽  
Squeezed States ◽  
Gaussian States ◽  
Fock States ◽  
The Past ◽  
Fidelity Measure ◽  
Non Gaussian ◽  
Thermal States

We study two families of four-photon superpositions of the Fock states: even vacuum squeezed states (EVSS) and orthogonal-even coherent states (OECS). These families are distinguished due to several properties: for certain values of parameters, they give the fourth-order uncertainty products close to the known minimal value (which is lower than for the Gaussian states); they have equal dimensionless values of the second- and fouth-order moments of the coordinate and momentum for all values of parameters; they possess zero covariances for all values of parameters. Since these states are obviously non-Gaussian, we consider them as good candidates to compare several different measures of non-Gaussianity proposed by different authors for the past fifteen years. The reference Gaussian states in all examples are thermal states dependent on a single parameter (an effective temperature or the coordinate variance). We analyze the measures based on the normalized Hilbert–Schmidt distance and the relative entropy (introduced by Genoni–Paris–Banaszek), the fidelity measure (Ghiu–Marian–Marian) and its logarithmic analog (Baek–Nha), as well as the Mandilara–Karpov–Cerf “Gaussianity parameter”. These measures are compared with the kurtosis of the coordinate probability density and with the non-Gaussian behavior of the Wigner function.

scholarly journals Non-Gaussian Cloning of Quantum Coherent States is Optimal

2005 ◽  
Vol 95 (7) ◽  
Author(s):  
N. J. Cerf ◽  
O. Krüger ◽  
P. Navez ◽  
R. F. Werner ◽  
M. M. Wolf
Keyword(s):  
Coherent States ◽  
Non Gaussian

Measure of non-Gaussianity for photon-added nonlinear coherent states

2018 ◽  
Vol 15 (09) ◽  
pp. 1850158
Author(s):  
K. Berrada ◽  
H. Eleuch
Keyword(s):  
Coherent State ◽  
Coherent States ◽  
Deformation Parameter ◽  
Critical Value ◽  
Statistical Properties ◽  
Noncommutative Space ◽  
Mandel’S Parameter ◽  
Generalized Coherent States ◽  
Non Gaussian

In this paper, we study the non-Gaussian character in generalized coherent states in the framework of a noncommutative space by adding photons to deformed coherent states, which is called the photon-added nonlinear coherent states (PANCSs). We find that the non-Gaussianity of PANCSs is enhanced with the increase of the photon-added number and it increases monotonically with the amplitude of the coherent states. Interestingly, we obtain that the maximal value of non-Gaussianity measure occurs at a certain critical value of the coherent state amplitude, where this critical value is determined by the kind of the deformation. Using the Mandel’s parameter, we examine the statistical properties for the PANCSs and show that the Mandel’s parameter may take positive and negative values depending on the choice of the amplitude and deformation parameter, exhibiting sub-Poissonian distribution and super-Poissonian distribution.

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