scholarly journals Quasi-probability information in a coupled two-qubit system interacting non-linearly with a coherent cavity under intrinsic decoherence

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Abdel-Baset A. Mohamed ◽  
Hichem Eleuch
Keyword(s):  
Phase Space ◽  
Quantum Coherence ◽  
Coupling Constants ◽  
Light Quantum ◽  
Wehrl Entropy ◽  
Intrinsic Decoherence ◽  
Highly Sensitive ◽  
Qubit System ◽  
Probability Information ◽  
Q Function

AbstractWe explore the phase space quantum effects, quantum coherence and non-classicality, for two coupled identical qubits with intrinsic decoherence. The two qubits are in a nonlinear interaction with a quantum field via an intensity-dependent coupling. We investigate the non-classicality via the Wigner functions. We also study the phase space information and the quantum coherence via the Q-function, Wehrl density, and Wehrl entropy. It is found that the robustness of the non-classicality for the superposition of coherent states, is highly sensitive to the coupling constants. The phase space quantum information and the matter-light quantum coherence can be controlled by the two-qubit coupling, initial cavity-field and the intrinsic decoherence.

scholarly journals Influence of the Coupling between Two Qubits in an Open Coherent Cavity: Nonclassical Information via Quasi-Probability Distributions

Entropy ◽  
2019 ◽  
Vol 21 (12) ◽  
pp. 1137 ◽  
Author(s):  
Abdel-Baset A. Mohamed ◽  
Hichem Eleuch ◽  
Abdel-Shafy F. Obada
Keyword(s):  
Quantum Coherence ◽  
Probability Distributions ◽  
Microwave Cavity ◽  
Wehrl Entropy ◽  
Intrinsic Decoherence ◽  
Probability Functions ◽  
Decoherence Rate ◽  
Two Level Systems ◽  
Q Function ◽  
Nonclassical Information

In this paper, we investigate the dynamics of two coupled two-level systems (or qubits) that are resonantly interacting with a microwave cavity. We examine the effects of the intrinsic decoherence rate and the coupling between the two qubits on the non-classicality of different system partitions via quasi-probability functions. New definitions for the partial Q-function and its Wehrl entropy are used to investigate the information and the quantum coherence of the phase space. The amount of the quantum coherence and non-classicality can be appropriately tuned by suitably adopting the rates of the intrinsic-decoherence and the coupling between the two qubits. The intrinsic decoherence has a pronounced effect on the negativity and the positivity of the Wigner function. The coupling between the two qubits can control the negativity and positivity of the quasi-probability functions.

ATOMIC WEHRL ENTROPY OF A SINGLE QUBIT SYSTEM

2011 ◽  
Vol 09 (03) ◽  
pp. 967-979 ◽  
Author(s):  
S. ABDEL-KHALEK ◽  
H. F. ABDEL-HAMEED ◽  
M. ABDEL-ATY
Keyword(s):  
Hilbert Space ◽  
Density Operator ◽  
Center Of Mass ◽  
Level System ◽  
Initial State ◽  
Wehrl Entropy ◽  
Trapped Ion ◽  
Single Qubit ◽  
Qubit System ◽  
Q Function

We propose the use of atomic Wehrl entropy associated to the reduced atomic density operator as an entanglement indicator of bipartite systems. This is applied to a two-level system (one single harmonically trapped ion) by taking into account the linear center-of-mass-motional degree of freedom. Detailed analytical and explicit expressions are given, taking into account different configurations. The results show the important roles played by the laser phase and initial state setting in the evolution of the atomic Q-function, atomic Wehrl entropy and marginal atomic Q-function. Our procedure of using atomic Wehrl entropy may be applied to a system with Hilbert space of high dimension.

scholarly journals Nonclassical Effects Based on Husimi Distributions in Two Open Cavities Linked by an Optical Waveguide

Entropy ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 767
Author(s):  
Abdel-Baset A. Mohamed ◽  
Hichem Eleuch
Keyword(s):  
Phase Space ◽  
Quantum Wells ◽  
Optical Waveguide ◽  
Quantum Coherence ◽  
Physical Parameters ◽  
Medium Density ◽  
Wehrl Entropy ◽  
Optical Medium ◽  
Optical Susceptibility ◽  
Open Cavities

Nonclassical effects are investigated in a system formed by two quantum wells, each of which is inside an open cavity. The cavities are spatially separated, linked by a fiber, and filled with a linear optical medium. Based on Husimi distributions (HDs) and Wehrl entropy, we explore the effects of the physical parameters on the generation and the robustness of the mixedness and HD information in the phase space. The generated quantum coherence and the HD information depend crucially on the cavity-exciton and fiber cavity couplings as well as on the optical medium density. The HD information and purity are lost due to the dissipation. This loss may be inhibited by increasing the optical susceptibility as well as the couplings of the exciton-cavity and the fiber-cavity. These parameters control the regularity, amplitudes, and frequencies of the generated mixedness.

scholarly journals Author Correction: Quasi-probability information in a coupled two-qubit system interacting non-linearly with a coherent cavity under intrinsic decoherence

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Abdel‑Baset A. Mohamed ◽  
Hichem Eleuch
Keyword(s):  
Intrinsic Decoherence ◽  
Qubit System ◽  
Probability Information

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Frozen Quantum Coherence for a Central Two-Qubit System in a Spin-Chain Environment

2018 ◽  
Vol 35 (8) ◽  
pp. 080301
Author(s):  
Yang Yang ◽  
An-Min Wang ◽  
Lian-Zhen Cao ◽  
Jia-Qiang Zhao ◽  
Huai-Xin Lu
Keyword(s):  
Spin Chain ◽  
Quantum Coherence ◽  
Qubit System

scholarly journals Tryptophan glycoconjugates in food and human urine*

1999 ◽  
Vol 343 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Birgit GUTSCHE ◽  
Christoph GRUN ◽  
Dieter SCHEUTZOW ◽  
Markus HERDERICH
Keyword(s):  
Human Urine ◽  
Quantum Coherence ◽  
Nuclear Overhauser Effect ◽  
Multiple Bond ◽  
Spatial Arrangement ◽  
Coupling Constants ◽  
Tandem Ms ◽  
Multiple Quantum ◽  
Hydroxymethyl Group ◽  
Ms Analysis

Evaluating the formation of tryptophan glycoconjugates other than well-established Amadori rearrangement products, HPLC-tandem MS (MS/MS) analysis of human urine collected from several healthy individuals proved the presence of one distinct tryptophan C-glycosyl compound [Horiuchi, Yonekawa, Iwahara, Kanno, Kurihara and Fujise (1994) J. Biochem. (Tokyo) 115, 362-366]. After isolation, unambiguous identification of this novel tryptophan metabolite as 2-(α-mannopyranosyl)-L-tryptophan was achieved by tandem MS combined with NMR spectroscopy including homonuclear COSY, heteronuclear multiple-bond connectivity and 1H-detected heteronuclear multiple-quantum coherence experiments. Remarkably, a thorough evaluation of vicinal proton-proton coupling constants in different solvents and nuclear Overhauser effect experiments demonstrate the predominant axial orientation of the hydroxymethyl group of the hexopyranosyl residue. Likewise this spatial arrangement indicates that the respective α-anomeric C-mannosylhexopyranose is preferentially adopting a 1C4 conformation in acidic methanol. Whereas only one distinct tryptophan mannoconjugate could be observed in human urine, HPLC-MS/MS analysis of food samples for the first time led to the identification of numerous N1-(β-D-hexopyranosyl)-L-tryptophan, 2-(β-D-hexopyranosyl)-L-tryptophan and 1-(1,2,3,4,5-p e n t a h y d r o x y p e n t - 1 - yl) - 1, 2, 3, 4 - t e t r a h y d r o - β - c a r b o l i n e - 3 -carboxylic acid derivatives derived from the condensation of tryptophan with aldohexoses. Taking into consideration the significant differences between profiles and configurations of tryptophan glycoconjugates originating from dietary sources and human urine, C-2 mannosylation of tryptophan residues [de Beer, Vliegenthart, Loeffler and Hofsteenge (1995) Biochemistry 34, 11785-11789] represents a novel enzymic pathway in tryptophan metabolism in humans.

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