scholarly journals Dynamics of three-qubit systems in a noisy environment

2016 ◽  
Vol 94 (2) ◽  
pp. 170-176 ◽  
Author(s):  
N. Metwally ◽  
A. Almannaei
Keyword(s):  
Sudden Death ◽  
Ghz State ◽  
W State ◽  
Correlated Noise ◽  
Entanglement Sudden Death ◽  
Noisy Environment ◽  
Initial State ◽  
W States ◽  
Noise Type

Some properties of three-qubit systems interacting with a noisy environment are discussed. The amount of the survival entanglement is quantified for the Greenberger–Horne–Zeilinger (GHZ) and W states. It is shown that the entanglement decay depends on the noise type (correlated or non-correlated), the number of interacting qubits with the environment, and the initial state that passes through this noisy environment. In general, the GHZ state is more fragile than the W state. The phenomenon of entanglement sudden death appears in the GHZ state only for non-correlated noise.

ENTANGLEMENT EVOLUTION OF A PAIR OF TWO-LEVEL SYSTEMS IN NON-MARKOVIAN ENVIRONMENT

2009 ◽  
Vol 07 (01) ◽  
pp. 385-393 ◽  
Author(s):  
X. L. HUANG ◽  
L. C. WANG ◽  
X. X. YI
Keyword(s):  
Sudden Death ◽  
Time Scale ◽  
Mutual Interaction ◽  
Short Time Scale ◽  
Entanglement Sudden Death ◽  
Initial State ◽  
Entanglement Evolution ◽  
Long Time ◽  
Two Level Systems ◽  
Short Time

The entanglement evolution of a pair of two-level systems is studied in this paper. The two systems without mutual interaction are independently coupled to different two-band non-Markovian environments. By comparing our results to others in the literature, we find that taking one of the Bell states as the initial state, certain non-Markovian effect protects the entanglement in short time scale, while on long time scale it leads to the entanglement sudden death (ESD), which never occurs for this initial state in the Markovian case. Finally, by analyzing the parameters in our model, a relation between disentanglement and decoherence is established and discussed.

scholarly journals Asymptotic Entanglement Sudden Death in Two Atoms with Dipole–Dipole and Ising Interactions Coupled to a Radiation Field at Non-Zero Detuning

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 629
Author(s):  
Gehad Sadiek ◽  
Wiam Al-Dress ◽  
Salwa Shaglel ◽  
Hala Elhag
Keyword(s):  
Asymptotic Behavior ◽  
Sudden Death ◽  
Radiation Field ◽  
Quantum Correlation ◽  
Bell State ◽  
Single Mode ◽  
Mean Value ◽  
Entanglement Sudden Death ◽  
Initial State ◽  
System Parameters

We investigate the time evolution and asymptotic behavior of a system of two two-level atoms (qubits) interacting off-resonance with a single mode radiation field. The two atoms are coupled to each other through dipole--dipole as well as Ising interactions. An exact analytic solution for the system dynamics that spans the entire phase space is provided. We focus on initial states that cause the system to evolve to entanglement sudden death (ESD) between the two atoms. We find that combining the Ising and dipole--dipole interactions is very powerful in controlling the entanglement dynamics and ESD compared with either one of them separately. Their effects on eliminating ESD may add up constructively or destructively depending on the type of Ising interaction (Ferromagnetic or anti-Ferromagnetic), the detuning parameter value, and the initial state of the system. The asymptotic behavior of the ESD is found to depend substantially on the initial state of the system, where ESD can be entirely eliminated by tuning the system parameters except in the case of an initial correlated Bell state. Interestingly, the entanglement, atomic population and quantum correlation between the two atoms and the field synchronize and reach asymptotically quasi-steady dynamic states. Each one of them ends up as a continuous irregular oscillation, where the collapse periods vanish, with a limited amplitude and an approximately constant mean value that depend on the initial state and the system parameters choice. This indicates an asymptotic continuous exchange of energy (and strong quantum correlation) between the atoms and the field takes place, accompanied by diminished ESD for these chosen setups of the system. This system can be realized in spin states of quantum dots or Rydberg atoms in optical cavities, and superconducting or hybrid qubits in linear resonators.

Enhancing entanglement of two-qubit states from amplitude damping channel using single-qubit unitary operation and local filtering operation

2021 ◽  
pp. 2150007
Author(s):  
Xiao-Lan Zong ◽  
Wei Song ◽  
Ming Yang ◽  
Zhuo-Liang Cao
Keyword(s):  
Sudden Death ◽  
Entanglement Sudden Death ◽  
Initial State ◽  
Amplitude Damping ◽  
Single Qubit ◽  
Death Time ◽  
Amplitude Damping Channel ◽  
State Formula ◽  
Qubit Operation ◽  
Local Filtering

We propose a scheme to enhance entanglement from amplitude damping or correlated amplitude damping decoherence. We show that entanglement sudden death time can be prolonged by the initial single-qubit operation combined with local filtering operation. For the amplitude damping channel case, we give the optimal single-qubit operation for arbitrary pure state [Formula: see text]. For the correlated amplitude damping channel case, we find that single-qubit operation on the initial state can not only enhance the final entanglement but also avoid entanglement sudden death. Compared to the previous schemes, the optimal operations and local filtering operations used in our scheme are independent with the decay parameters of the environment.

scholarly journals Manipulation of entanglement sudden death in an all-optical setup

2017 ◽  
Vol 34 (3) ◽  
pp. 681 ◽  
Author(s):  
Ashutosh Singh ◽  
Siva Pradyumna ◽  
A. R. P. Rau ◽  
Urbasi Sinha
Keyword(s):  
Sudden Death ◽  
Entanglement Sudden Death ◽  
Optical Setup ◽  
All Optical

Coherent state quantum key distribution based on entanglement sudden death

2015 ◽  
Vol 15 (3) ◽  
pp. 1117-1133
Author(s):  
Gregg Jaeger ◽  
David Simon ◽  
Alexander V. Sergienko
Keyword(s):  
Sudden Death ◽  
Coherent State ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Entanglement Sudden Death

Entanglement criteria for the three-qubit states

2017 ◽  
Vol 15 (07) ◽  
pp. 1750049 ◽  
Author(s):  
Y. Akbari-Kourbolagh
Keyword(s):  
White Noise ◽  
Tensor Products ◽  
W State ◽  
Entangled States ◽  
Mean Values ◽  
W States ◽  
Pauli Matrices ◽  
The Mean ◽  
Simple Sets ◽  
Qubit States

We present sufficient criteria for the entanglement of three-qubit states. For some special families of states, the criteria are also necessary for the entanglement. They are formulated as simple sets of inequalities for the mean values of certain observables defined as tensor products of Pauli matrices. The criteria are good indicators of the entanglement in the vicinity of three-qubit GHZ and W states and enjoy the capability of detecting the entangled states with positive partial transpositions. Furthermore, they improve the best known result for the case of W state mixed with the white noise. The efficiency of the criteria is illustrated through several examples.

Fusion of W states in a cavity quantum electrodynamic system

2015 ◽  
Vol 93 (5) ◽  
pp. 556-560 ◽  
Author(s):  
Xue-Ping Zang ◽  
Ming Yang ◽  
Xian-Cai Wang ◽  
Wei Song ◽  
Zhuo-Liang Cao
Keyword(s):  
Quantum Electrodynamic ◽  
Cavity Mode ◽  
State System ◽  
The Other ◽  
W State ◽  
Feasibility Analysis ◽  
Electrodynamic System ◽  
W States ◽  
Vacuum Cavity

In this paper, we study how to fuse two W states into a larger W state in a cavity quantum electrodynamic system. Two atoms are collided within a detuned vacuum cavity mode. One atom is from the first N-atom W state system, and the other is from the second M-atom W state system. The two atoms will be detected after flying out of the cavity mode. If only one excitation is detected between the two atoms, an (N + M − 2)-atom W state can be generated with some probability. If no excitation is detected between the two atoms, the remaining (N − 1)-atom W state and (M − 1)-atom W state can be re-fused using the same procedure, continuing until two excitations are detected between the two atoms. Using this procedure, the chance of entanglement of the two W states is as large as possible. A feasibility analysis indicates that this scheme can be implemented using existing experimental technologies.

Entanglement sudden death via two-photon processes in cavity QED

2009 ◽  
Vol 42 (19) ◽  
pp. 195507 ◽  
Author(s):  
W B Cardoso ◽  
A T Avelar ◽  
B Baseia ◽  
N G de Almeida
Keyword(s):  
Sudden Death ◽  
Cavity Qed ◽  
Entanglement Sudden Death ◽  
Two Photon

The computational power of the W and GHZ states

2006 ◽  
Vol 6 (2) ◽  
pp. 173-183
Author(s):  
E. D'Hondt ◽  
P. Panangaden
Keyword(s):  
Pure State ◽  
Lie Symmetry ◽  
Leader Election ◽  
Ghz State ◽  
W State ◽  
Computational Power ◽  
Post Processing ◽  
Distributed Consensus ◽  
Quantum Networks ◽  
Impossibility Results

It is well understood that the use of quantum entanglement significantly enhances the computational power of systems. Much of the attention has focused on Bell states and their multipartite generalizations. However, in the multipartite case it is known that there are several inequivalent classes of states, such as those represented by the W-state and the GHZ-state. Our main contribution is a demonstration of the special computational power of these states in the context of paradigmatic problems from classical distributed computing. Concretely, we show that the W-state is the only pure state that can be used to exactly solve the problem of leader election in anonymous quantum networks. Similarly we show that the GHZ-state is the only one that can be used to solve the problem of distributed consensus when no classical post-processing is considered. These results generalize to a family of W- and GHZ-like states. At the heart of the proofs of these impossibility results lie symmetry arguments.

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