USEFULNESS CLASSES OF TRAVELING ENTANGLED CHANNELS IN NONINERTIAL FRAMES

2013 ◽  
Vol 27 (28) ◽  
pp. 1350155 ◽  
Author(s):  
N. METWALLY
Keyword(s):  
Pure State ◽  
Quantum Teleportation ◽  
The Self ◽  
Entangled States ◽  
Quantum Channels ◽  
Werner State ◽  
Qubit System ◽  
Pure States

The dynamics of a general two qubit system in a noninetrial frame is investigated analytically, where it is assumed that both of its subsystems are differently accelerated. Two classes of initial traveling states are considered: self-transposed and generic pure states. The entanglement contained in all possible generated entangled states between the qubits and their anti-qubits is quantified. The usefulness of the traveling states as quantum channels to perform quantum teleportation is investigated. For the self-transposed classes, it is shown that the generalized Werner state is the most robust class and starting from a class of pure state, one can generate entangled states more robust than self-transposed classes.

scholarly journals Graph Approach to Quantum Teleportation Dynamics

2020 ◽  
Vol 2 (3) ◽  
pp. 352-377
Author(s):  
Efrén Honrubia ◽  
Ángel S. Sanz
Keyword(s):  
Quantum Information ◽  
Quantum Teleportation ◽  
Entangled States ◽  
Quantum Channels ◽  
Qubit System ◽  
Alternative Approaches ◽  
Maximally Entangled States ◽  
Usual State ◽  
Vector Description ◽  
Direct Correspondence

Quantum teleportation plays a key role in modern quantum technologies. Thus, it is of much interest to generate alternative approaches or representations that are aimed at allowing us a better understanding of the physics involved in the process from different perspectives. With this purpose, here an approach based on graph theory is introduced and discussed in the context of some applications. Its main goal is to provide a fully symbolic framework for quantum teleportation from a dynamical viewpoint, which makes explicit at each stage of the process how entanglement and information swap among the qubits involved in it. In order to construct this dynamical perspective, it has been necessary to define some auxiliary elements, namely virtual nodes and edges, as well as an additional notation for nodes describing potential states (against nodes accounting for actual states). With these elements, not only the flow of the process can be followed step by step, but they also allow us to establish a direct correspondence between this graph-based approach and the usual state vector description. To show the suitability and versatility of this graph-based approach, several particular teleportation examples are examined in detail, which include bipartite, tripartite, and tetrapartite maximally entangled states as quantum channels. From the analysis of these cases, a general protocol is devised to describe the sharing of quantum information in presence of maximally entangled multi-qubit system.

REMOTE PREPARATION OF AN ARBITRARY TWO-PARTICLE PURE STATE VIA NONMAXIMALLY ENTANGLED STATES AND POSITIVE OPERATOR-VALUED MEASUREMENT

2010 ◽  
Vol 08 (08) ◽  
pp. 1265-1275 ◽  
Author(s):  
DONG WANG
Keyword(s):  
Positive Operator ◽  
Pure State ◽  
Success Probability ◽  
Entangled States ◽  
Quantum Channels ◽  
Pure States ◽  
Auxiliary Particles ◽  
Remote Preparation

A scheme for remotely preparing an arbitrary two-particle pure state is proposed by employing bipartite nonmaximally entangled states as quantum channels. During the preparation, two auxiliary particles and an optimal positive operator-valued measurement are introduced. The preparation of two-particle pure states can be remotely realized with certain success probability (SP). And the SP of our scheme is exactly worked out. It turns out that the SP depends inherently on the quantum channels employed beforehand. Furthermore, we find that, as far as two special ensembles of two-particle states are concerned, i.e. real and equatorial-like, the SP can be enhanced to quadruple.

scholarly journals Probabilistic Resumable Quantum Teleportation of a Two-Qubit Entangled State

Entropy ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 352 ◽  
Author(s):  
Zhan-Yun Wang ◽  
Yi-Tao Gou ◽  
Jin-Xing Hou ◽  
Li-Ke Cao ◽  
Xiao-Hui Wang
Keyword(s):  
Quantum Channel ◽  
Quantum Teleportation ◽  
The State ◽  
Entangled States ◽  
Entangled State ◽  
Quantum Channels ◽  
Unknown State ◽  
Optimal Probability

We explicitly present a generalized quantum teleportation of a two-qubit entangled state protocol, which uses two pairs of partially entangled particles as quantum channel. We verify that the optimal probability of successful teleportation is determined by the smallest superposition coefficient of these partially entangled particles. However, the two-qubit entangled state to be teleported will be destroyed if teleportation fails. To solve this problem, we show a more sophisticated probabilistic resumable quantum teleportation scheme of a two-qubit entangled state, where the state to be teleported can be recovered by the sender when teleportation fails. Thus the information of the unknown state is retained during the process. Accordingly, we can repeat the teleportion process as many times as one has available quantum channels. Therefore, the quantum channels with weak entanglement can also be used to teleport unknown two-qubit entangled states successfully with a high number of repetitions, and for channels with strong entanglement only a small number of repetitions are required to guarantee successful teleportation.

Most robust and fragile two-qubit entangled states under deploarizing channels

2013 ◽  
Vol 13 (7&8) ◽  
pp. 645-660
Author(s):  
Chao-Qian Pang ◽  
Fu-Lin Zhang ◽  
Yue Jiang ◽  
Mai-Lin Liang ◽  
Jing-Ling Chen
Keyword(s):  
Evolution Equation ◽  
Numerical Calculations ◽  
Entangled States ◽  
Fragile States ◽  
Qubit System ◽  
Uniform Channel ◽  
Pure States ◽  
The One ◽  
Major Factors ◽  
The Impact

For a two-qubit system under local depolarizing channels, the most robust and most fragile states are derived for a given concurrence or negativity. For the one-sided channel, the pure states are proved to be the most robust ones, with the aid of the evolution equation for entanglement given by Konrad \emph{et al.} [Nat. Phys. 4, 99 (2008)]. Based on a generalization of the evolution equation for entanglement, we classify the ansatz states in our investigation by the amount of robustness, and consequently derive the most fragile states. For the two-sided channel, the pure states are the most robust for a fixed concurrence. Under the uniform channel, the most fragile states have the minimal negativity when the concurrence is given in the region $[1/2,1]$. For a given negativity, the most robust states are the ones with the maximal concurrence, and the most fragile ones are the pure states with minimum of concurrence. When the entanglement approaches zero, the most fragile states under general nonuniform channels tend to the ones in the uniform channel. Influences on robustness by entanglement, degree of mixture, and asymmetry between the two qubits are discussed through numerical calculations. It turns out that the concurrence and negativity are major factors for the robustness. When they are fixed, the impact of the mixedness becomes obvious. In the nonuniform channels, the most fragile states are closely correlated with the asymmetry, while the most robust ones with the degree of mixture.

scholarly journals Teleportation via maximally and non-maximally entangled mixed states

2010 ◽  
Vol 10 (5&6) ◽  
pp. 398-419
Author(s):  
S. Adhikari ◽  
A.S. Majumdar ◽  
S. Roy ◽  
B. Ghosh ◽  
N. Nayak
Keyword(s):  
Mixed State ◽  
Quantum Teleportation ◽  
Convex Combination ◽  
Type Inequality ◽  
Entangled States ◽  
Mixed States ◽  
Werner State ◽  
Parameter Values

We study the efficiency of two-qubit mixed entangled states as resources for quantum teleportation. We first consider two maximally entangled mixed states, viz., the Werner state\cite{werner}, and a class of states introduced by Munro {\it et al.} \cite{munro}. We show that the Werner state when used as teleportation channel, gives rise to better average teleportation fidelity compared to the latter class of states for any finite value of mixedness. We then introduce a non-maximally entangled mixed state obtained as a convex combination of a two-qubit entangled mixed state and a two-qubit separable mixed state. It is shown that such a teleportation channel can outperform another non-maximally entangled channel, viz., the Werner derivative for a certain range of mixedness. Further, there exists a range of parameter values where the former state satisfies a Bell-CHSH type inequality and still performs better as a teleportation channel compared to the Werner derivative even though the latter violates the inequality.

Cyclic quantum teleportation of an unknown multi-particle high-dimension state

2020 ◽  
Vol 34 (05) ◽  
pp. 2050073
Author(s):  
Fan Wu ◽  
Ming-Qiang Bai ◽  
Yu-Chun Zhang ◽  
Ren-Ju Liu ◽  
Zhi-Wen Mo
Keyword(s):  
High Dimension ◽  
Quantum Teleportation ◽  
Bell State ◽  
Measurement Methods ◽  
Entangled States ◽  
Quantum Channels ◽  
State Measurement ◽  
Probabilistic Teleportation ◽  
Particle Measurement ◽  
Single Particle Measurement

In this paper, via 12-particle entangled states as quantum channels, two schemes for cyclic quantum teleportation are proposed by using two different measurement methods, one is the Bell state measurement, the other is single-particle measurement. Besides, these schemes can be generalized to realize the probabilistic teleportation of an unknown multi-particle high-dimension state. Furthermore, feasibility for the schemes and some conclusions are discussed at the end of this paper.

Robustness of two-qubit and three-qubit states in correlated quantum channels

2022 ◽  
Author(s):  
Zhan-Yun Wang ◽  
Feng-Lin Wu ◽  
Zhen-Yu Peng ◽  
Si-Yuan Liu
Keyword(s):  
Entangled States ◽  
Fragile States ◽  
Quantum Channels ◽  
Noisy Channels ◽  
Correlated Channels ◽  
Pure States ◽  
Bit Flip ◽  
Qubit States

Abstract We investigate how the correlated actions of quantum channels affect the robustness of entangled states. We consider the Bell-like state and random two-qubit pure states in the correlated depolarizing, bit flip, bit-phase flip, and phase flip channels. It is found that the robustness of two-qubit pure states can be noticeably enhanced due to the correlations between consecutive actions of these noisy channels, and the Bell-like state is always the most robust state. We also consider the robustness of three-qubit pure states in correlated noisy channels. For the correlated bit flip and phase flip channels, the result shows that although the most robust and most fragile states are locally unitary equivalent, they exhibit different robustness in different correlated channels, and the effect of channel correlations on them is also significantly different. However, for the correlated depolarizing and bit-phase flip channels, the robustness of two special three-qubit pure states is exactly the same. Moreover, compared with the random three-qubit pure states, they are neither the most robust states nor the most fragile states.

scholarly journals Optimal teleportation via noisy quantum channels without additional qubit resources

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Dong-Gil Im ◽  
Chung-Hyun Lee ◽  
Yosep Kim ◽  
Hyunchul Nha ◽  
M. S. Kim ◽  
...  
Keyword(s):  
Quantum Computing ◽  
Quantum Teleportation ◽  
Quantum Communication ◽  
Quantum Noise ◽  
Single Copy ◽  
Entangled State ◽  
Quantum Network ◽  
Quantum Channels ◽  
Maximally Entangled State ◽  
Near Term

AbstractQuantum teleportation exemplifies how the transmission of quantum information starkly differs from that of classical information and serves as a key protocol for quantum communication and quantum computing. While an ideal teleportation protocol requires noiseless quantum channels to share a pure maximally entangled state, the reality is that shared entanglement is often severely degraded due to various decoherence mechanisms. Although the quantum noise induced by the decoherence is indeed a major obstacle to realizing a near-term quantum network or processor with a limited number of qubits, the methodologies considered thus far to address this issue are resource-intensive. Here, we demonstrate a protocol that allows optimal quantum teleportation via noisy quantum channels without additional qubit resources. By analyzing teleportation in the framework of generalized quantum measurement, we optimize the teleportation protocol for noisy quantum channels. In particular, we experimentally demonstrate that our protocol enables to teleport an unknown qubit even via a single copy of an entangled state under strong decoherence that would otherwise preclude any quantum operation. Our work provides a useful methodology for practically coping with decoherence with a limited number of qubits and paves the way for realizing noisy intermediate-scale quantum computing and quantum communication.

CONTROLLED TELEPORTATION OF ELECTRON SPIN STATE IN QUANTUM DOT VIA SINGLE PHOTON

2008 ◽  
Vol 06 (03) ◽  
pp. 553-560
Author(s):  
YAN-WEI WANG ◽  
MING-FENG WANG ◽  
YI-ZHUANG ZHENG
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Electron Spin ◽  
Spin State ◽  
Faraday Rotation ◽  
Quantum Teleportation ◽  
Single Photon ◽  
Controlled Teleportation ◽  
Controlled Quantum Teleportation ◽  
Qubit System

A controlled quantum teleportation scheme of electron spin state in a quantum dot is proposed. With the entanglement generating through the interaction between the quantum dots in microcavities and a single photon, the controlled teleportation can be implemented using Faraday rotation and single photon measurements. The scheme can be easily generalized to multi-qubit system.

scholarly journals Construction of genuinely entangled subspacesand the associated bounds on entanglement measures for mixed states

2021 ◽  
Author(s):  
Konstantin Antipin
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Lower Bounds ◽  
Quantum Information Processing ◽  
Multipartite Entanglement ◽  
Quantum Channels ◽  
Valuable Resource ◽  
Mixed States ◽  
Entanglement Measures ◽  
Pure States

Abstract Genuine entanglement is the strongest form of multipartite entanglement. Genuinely entangled pure states contain entanglement in every bipartition and as such can be regarded as a valuable resource in the protocols of quantum information processing. A recent direction of research is the construction of genuinely entangled subspaces — the class of subspaces consisting entirely of genuinely entangled pure states. In this paper we present methods of construction of such subspaces including those of maximal possible dimension. The approach is based on the composition of bipartite entangled subspaces and quantum channels of certain types. The examples include maximal subspaces for systems of three qubits, four qubits, three qutrits. We also provide lower bounds on two entanglement measures for mixed states, the concurrence and the convex-roof extended negativity, which are directly connected with the projection on genuinely entangled subspaces.

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