Dynamics of multi-qubit states in non-inertial frames for quantum communication applications

2014 ◽  
Vol 14 (3&4) ◽  
pp. 255-264
Author(s):  
Alaa Sagheer ◽  
Hala Hamdoun
Keyword(s):  
Degradation Rate ◽  
Quantum Communication ◽  
Ghz State ◽  
The Other ◽  
W State ◽  
Entangled States ◽  
Inertial Frames ◽  
Qubit States ◽  
Degree Of Entanglement ◽  
Accelerated Frames

In this paper, some properties of multi-qubit states traveling in non-inertial frames are investigated, where we assume that all particles are accelerated. These properties are including fidelities, capacities and entanglement of the accelerated channels for three different states, namely, Greeberger-Horne-Zeilinger (GHZ) state, GHZ-like state and W-state. It is shown here that all these properties are decreased as the accelerations of the moving particles are increased. The obtained results show that the GHZ-state is the most robust state comparing to the others, where the degradation rate is less than that for the other states particularly in the second Rindler region. Also, it is shown here that the entangled property doesn't change in the accelerated frames. Additionally, the paper shows that the degree of entanglement decreases as the accelerations of the particles increase in the first Rindler region. However in the second region, where all subsystems are disconnected at zero acceleration, entangled states are generated as the acceleration increases.

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.

scholarly journals Standard (3, 5)-threshold quantum secret sharing by maximally entangled 6-qubit states

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yinxiang Long ◽  
Cai Zhang ◽  
Zhiwei Sun
Keyword(s):  
Secret Sharing ◽  
Quantum Secret Sharing ◽  
The Other ◽  
Entangled States ◽  
Secret Sharing Schemes ◽  
Secret Sharing Scheme ◽  
Sharing Scheme ◽  
Qubit States ◽  
Quantum Secret Sharing Scheme

AbstractIn this paper, a standard (3, 5)-threshold quantum secret sharing scheme is presented, in which any three of five participants can resume cooperatively the classical secret from the dealer, but one or two shares contain absolutely no information about the secret. Our scheme can be fulfilled by using the singular properties of maximally entangled 6-qubit states found by Borras. We analyze the scheme’s security by several ways, for example, intercept-and-resend attack, entangle-and-measure attack, and so on. Compared with the other standard threshold quantum secret sharing schemes, our scheme needs neither to use d-level multipartite entangled states, nor to produce shares by classical secret splitting techniques, so it is feasible to be realized.

ENCRYPTION-BASED NETWORKING QUANTUM TELEPORTATION WITH TRIPLET GREENBERGER–HORNE–ZEILINGER STATES

2010 ◽  
Vol 08 (05) ◽  
pp. 765-778 ◽  
Author(s):  
YING GUO ◽  
Guihua Zeng
Keyword(s):  
Quantum Channel ◽  
Quantum Key Distribution ◽  
Quantum Teleportation ◽  
Quantum Communication ◽  
Ghz State ◽  
The Novel ◽  
Bell Measurement ◽  
Intrinsic Efficiency ◽  
Almost All ◽  
Qubit States

An encryption-based networking quantum teleportation scheme is proposed for the secure quantum communication network based on the novel networking quantum key distribution (NQKD) with the Greenberger–Horne–Zeilinger (GHZ) state. The security is exactly guaranteed via the entanglement of the GHZ quantum system. In the process of quantum teleportation, the server Charlie prepares the GHZ states and the users exploit the four local unitary operations corresponding to the keys shared aforehand to encrypt/decrpt for the initial messages. One legal user can communicate with another on the network securely as they may perform a quantum privacy application on the encrypted quantum states transmitted in quantum channel. Its intrinsic efficiency is high as almost all the instances are useful and each GHZ state can carry two different encrypted single-qubit states. To reconstruct these transmitted messages, the users exploit Bell measurement and perform local operations with respect to the shared keys in NQKD, which will improve its security in a noise quantum channel.

ENTANGLEMENT DYNAMICS OF THREE-QUBIT STATES UNDER A SPIN ENVIRONMENT

2011 ◽  
Vol 09 (02) ◽  
pp. 791-800 ◽  
Author(s):  
XIAO SAN MA ◽  
GAO SHENG LIU ◽  
AN MIN WANG
Keyword(s):  
Coupling Strength ◽  
Degrees Of Freedom ◽  
Ghz State ◽  
W State ◽  
Matrix Elements ◽  
Entanglement Dynamics ◽  
Werner State ◽  
Qubit States ◽  
Decoherence Free Subspaces

In this paper, we investigate the entanglement dynamics of three-qubit states under a spin environment. From the analysis, we find that the entanglement dynamics of the three-qubit states depends not only on the coupling strength between the system and the environment and the number of degrees of freedom of the environment but also on the tunneling matrix elements of the spin environment and the specific state of concern. Specifically, the entanglement dynamics of the GHZ state, the W state, and the Werner state have been analyzed in detail and the conditions to identify the decoherence-free subspaces of our model have been discussed.

scholarly journals Entangling three qubits without ever touching

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Pawel Blasiak ◽  
Marcin Markiewicz
Keyword(s):  
Ghz State ◽  
W State ◽  
Entangled States ◽  
Identical Particles ◽  
Practical Applications ◽  
Linear Optical ◽  
Anyon Statistics

AbstractAll identical particles are inherently correlated from the outset, regardless of how far apart their creation took place. In this paper, this fact is used for extraction of entanglement from independent particles unaffected by any interactions. Specifically, we are concerned with operational schemes for generation of all tripartite entangled states, essentially the GHZ state and the W state, which prevent the particles from touching one another over the entire evolution. The protocols discussed in the paper require only three particles in linear optical setups with equal efficiency for boson, fermion or anyon statistics. Within this framework indistinguishability of particles presents itself as a useful resource of entanglement accessible for practical applications.

SCHEME FOR THE PREPARATION OF ENTANGLEMENT OF ATOMIC ENSEMBLES

2009 ◽  
Vol 07 (08) ◽  
pp. 1459-1467 ◽  
Author(s):  
LIN-LIN XU ◽  
YA-FEI YU ◽  
ZHI-MING ZHANG
Keyword(s):  
Atomic System ◽  
Vacuum State ◽  
Classical Field ◽  
Ghz State ◽  
W State ◽  
Evolution Process ◽  
Entangled States ◽  
Atomic Ensemble ◽  
Atomic Ensembles ◽  
Cavity Decay

In this paper, we present a scheme to prepare the W state and the GHZ state of many atomic ensembles based on the dynamics of the atomic system of a single control atom and an atomic ensemble dispersively coupling with a cavity, where the control atom is illuminated by a highly detuned auxiliary classical field at the same time. The dynamics of the atomic system can be described by an effective Jaynes–Cummings model (JCM) with the atomic ensemble as the bosonic mode. The preparation of the entangled states is deterministic. Because the cavity is always in the vacuum state during the whole evolution process, our scheme is less sensitive to the cavity decay.

Optimal class-specific witnesses for three-qubit entanglement from Greenberger-Horne-Zeilinger symmetry

2013 ◽  
Vol 13 (3&4) ◽  
pp. 210-220
Author(s):  
Christopher Eltschka ◽  
Jens Siewert
Keyword(s):  
Ghz State ◽  
Quantum States ◽  
Point Of View ◽  
The Other ◽  
Mixed States ◽  
Other Hand ◽  
New Type ◽  
The One ◽  
Qubit States ◽  
Symmetric States

Recently, a new type of symmetry for three-qubit quantum states was introduced, the so-called Greenberger-Horne-Zeilinger (GHZ) symmetry. It includes the operations which leave the three-qubit standard GHZ state unchanged. This symmetry is powerful as it yields families of mixed states that are, on the one hand, complex enough from the physics point of view and, on the other hand, simple enough mathematically so that their properties can be characterized analytically. We show that by using the properties of GHZ-symmetric states it is straightforward to derive optimal witnesses for detecting class-specific entanglement in arbitrary three-qubit states.

CONTROLLED QUANTUM SECURE DIRECT COMMUNICATION WITH W STATE

2008 ◽  
Vol 06 (04) ◽  
pp. 899-906 ◽  
Author(s):  
XIU-BO CHEN ◽  
QIAO-YAN WEN ◽  
FEN-ZHUO GUO ◽  
YING SUN ◽  
GANG XU ◽  
...  
Keyword(s):  
Quantum Computation ◽  
Quantum Secure Direct Communication ◽  
Quantum Circuit ◽  
Ghz State ◽  
The Other ◽  
W State ◽  
Secret Message ◽  
Direct Communication ◽  
Other Hand

Utilizing W state, which is much more robust than GHZ state, we propose a protocol for three-party controlled quantum secure direct communication (QSDC). The feature of this protocol is that the sender encodes the secret message directly on a sequence of particle states and faithfully transmits them to an arbitrary one of two receivers without revealing any information to a potential eavesdropper. On the other hand, we construct the efficient quantum circuit to implement the QSDC by means of primitive operations in quantum computation.

scholarly journals Influence of Ceramic Particles Character on Resulted Properties of Zinc-Hydroxyapatite/Monetite Composites

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 499
Author(s):  
Klára Hosová ◽  
Jan Pinc ◽  
Andrea Školáková ◽  
Vilém Bartůněk ◽  
Petr Veřtát ◽  
...  
Keyword(s):  
Significant Influence ◽  
Degradation Rate ◽  
Point Of View ◽  
The Other ◽  
Ceramic Particles ◽  
Biological Aspects ◽  
Strength And Ductility

Zinc and its alloys seem to be promising candidates for biodegradable applications. Those materials are often modified by other elements or compounds in order to enhance their properties. The combination of zinc and apatites is challenging for several reasons. However, the advantages connected with the biological aspects suggest the need for further research into such materials. In this study, three zinc-based composites with 4 and 8 wt. % of nanohydroxyapatite or nanomonetite (Zn-4MO, Zn-4HA, Zn-8HA) were prepared by sintering and subsequent extrusion. Materials prepared in this way were characterized from the microstructural, mechanical and corrosion point of view. The obtained results showed a significant influence of particle character (amount and morphology) on the strength and ductility of the prepared materials. In case of Zn-4MO, the presence of monetite significantly increased the ductility compared with the other materials. In addition, the increment of the degradation rate caused by the presence of monetite was observed as well. All obtained results pointed out to significant advantages of monetite for the preparation of Zn-apatite composites compared with hydroxyapatite.

A matrix realignment method for recognizing entanglement

2003 ◽  
Vol 3 (3) ◽  
pp. 193-202
Author(s):  
K. Chen ◽  
L.-A. Wu
Keyword(s):  
Kronecker Product ◽  
Singular Values ◽  
Quantum Systems ◽  
Entangled States ◽  
Approximation Technique ◽  
Separable State ◽  
Simple Method ◽  
Bipartite Quantum Systems ◽  
The Matrix ◽  
Degree Of Entanglement

Motivated by the Kronecker product approximation technique, we have developed a very simple method to assess the inseparability of bipartite quantum systems, which is based on a realigned matrix constructed from the density matrix. For any separable state, the sum of the singular values of the matrix should be less than or equal to $1$. This condition provides a very simple, computable necessary criterion for separability, and shows powerful ability to identify most bound entangled states discussed in the literature. As a byproduct of the criterion, we give an estimate for the degree of entanglement of the quantum state.

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