Correlations, Nonlocality and Usefulness of an Efficient Class of Two-Qubit Mixed Entangled States

2018 ◽  
Vol 73 (3) ◽  
pp. 191-206 ◽  
Author(s):  
Parvinder Singh ◽  
Atul Kumar
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Weak Measurement ◽  
Analytical Relation ◽  
Entangled States ◽  
Mixed States ◽  
New Class ◽  
Chsh Inequality ◽  
Noisy Conditions

AbstractWe establish an analytical relation between the Bell-Clauser-Horne-Shimony-Holt (Bell-CHSH) inequality and weak measurement strengths under noisy conditions. We show that the analytical results obtained in this article are of utmost importance for proposing a new class of two-qubit mixed states for quantum information processing. Our analysis further shows that the states proposed here are better resources for quantum information in comparison to other two-qubit mixed entangled states.

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.

Manipulation of Entangled States for Quantum Information Processing

2005 ◽  
pp. 49-58 ◽  
Author(s):  
S. Bose ◽  
S. F. Huelga ◽  
D. Jonathan ◽  
P. L. Knight ◽  
M. Murao ◽  
...  
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Entangled States

scholarly journals Coherent preorder of quantum states

2020 ◽  
Vol 20 (13&14) ◽  
pp. 1124-1137
Author(s):  
Zhaofang Bai ◽  
Shuanping Shuanping Du
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Coherent States ◽  
Quantum Coherence ◽  
Quantum Information Processing ◽  
Quantum States ◽  
Mixed States ◽  
Quantum Hypothesis ◽  
Quantum Hypothesis Testing

As an important quantum resource, quantum coherence play key role in quantum information processing. It is often concerned with manipulation of families of quantum states rather than individual states in isolation. Given two pairs of coherent states $(\rho_1,\rho_2)$ and $(\sigma_1,\sigma_2)$, we are aimed to study how can we determine if there exists a strictly incoherent operation $\Phi$ such that $\Phi(\rho_i) =\sigma_i,i = 1,2$. This is also a classic question in quantum hypothesis testing. In this note, structural characterization of coherent preorder under strongly incoherent operations is provided. Basing on the characterization, we propose an approach to realize coherence distillation from rank-two mixed coherent states to $q$-level maximally coherent states. In addition, one scheme of coherence manipulation between rank-two mixed states is also presented.

Analysing the Efficiencies of Partially Entangled Three-Qubit States for Quantum Information Processing Under Real Conditions

2019 ◽  
Vol 74 (6) ◽  
pp. 523-537
Author(s):  
Jyoti Faujdar ◽  
Atul Kumar
Keyword(s):  
Quantum Information Processing ◽  
Weak Measurement ◽  
Entangled States ◽  
Entangled State ◽  
Maximally Entangled State ◽  
Prepared State ◽  
Noisy Conditions ◽  
Partially Entangled States ◽  
Robust To Noise ◽  
Qubit States

AbstractIn this article, we revisit the question of analysing the efficiencies of partially entangled states in three-qubit classes under real conditions. Our results show some interesting observations regarding the efficiencies and correlations of partially entangled states. Surprisingly, we find that the efficiencies of many three-qubit partially entangled states exceed that of maximally entangled three-qubit states under real noisy conditions and applications of weak measurements. Our analysis, therefore, suggests that the efficiencies of partially entangled states are much more robust to noise than those of maximally entangled states at least for the GHZ (Greenberger–Horne–Zeilinger) class states, for certain protocols; i.e. less correlations in the initially prepared state may also lead to better efficiency and hence one need not always consider starting with a maximally entangled state with maximum correlations between the qubits. For a set of partially entangled states, we find that the efficiency is optimal, independent of the decoherence and state parameters, if the value of weak measurement parameter is very large. For other values of the weak measurement parameter, the robustness of the states depends on the decoherence and state parameters. Moreover, we further show that one can achieve higher efficiencies in a protocol by using non-optimal weak measurement strengths instead of optimal weak measurement strengths.

scholarly journals Realizing a deterministic source of multipartite-entangled photonic qubits

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jean-Claude Besse ◽  
Kevin Reuer ◽  
Michele C. Collodo ◽  
Arne Wulff ◽  
Lucien Wernli ◽  
...  
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Electromagnetic Radiation ◽  
Quantum Information Processing ◽  
Entangled States ◽  
Experimental Setting ◽  
Many Body ◽  
Body State ◽  
Process Tomography ◽  
Multi Mode

Abstract Sources of entangled electromagnetic radiation are a cornerstone in quantum information processing and offer unique opportunities for the study of quantum many-body physics in a controlled experimental setting. Generation of multi-mode entangled states of radiation with a large entanglement length, that is neither probabilistic nor restricted to generate specific types of states, remains challenging. Here, we demonstrate the fully deterministic generation of purely photonic entangled states such as the cluster, GHZ, and W state by sequentially emitting microwave photons from a controlled auxiliary system into a waveguide. We tomographically reconstruct the entire quantum many-body state for up to N = 4 photonic modes and infer the quantum state for even larger N from process tomography. We estimate that localizable entanglement persists over a distance of approximately ten photonic qubits.

scholarly journals Device-independent verification of Einstein-Podolsky-Rosen steering

2021 ◽  
Author(s):  
Yuan-Yuan Zhao ◽  
Chao Zhang ◽  
Shuming Cheng ◽  
Xinhui Li ◽  
Yu Guo ◽  
...  
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Entangled States ◽  
Independent Verification ◽  
Self Testing ◽  
Experimental Implementation ◽  
Einstein Podolsky Rosen ◽  
Complete Framework ◽  
Epr Steering

Abstract If the presence of entanglement could be certified in a device-independent (DI) way, it is likely to provide various quantum information processing tasks with unconditional security. Recently, it was shown that a DI protocol, combining measurement-device-independent techniques with self-testing, is able to verify all entangled states, however, it imposes demanding requirements on its experimental implementation. In this work, we propose a much less-demanding protocol based on Einstein-Podolsky-Rosen (EPR) steering to certify entanglement. We establish a complete framework for DI verification of EPR steering in which all steerable states could be verified. We then analyze its robustness towards noise and imperfections of self-testing by considering the measurement scenario with three settings at each side. Finally, a four-photon experiment is implemented to demonstrate that even Bell local states can be device-independently verified. Our work may pave the way for realistic applications of secure quantum information tasks.

BASIC OPERATIONS AMONG ENTANGLED STATES AND THEIR APPLICATIONS TO QUANTUM PROTOCOLS

2006 ◽  
Vol 04 (02) ◽  
pp. 307-323
Author(s):  
TAKASHI MIHARA
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Entangled States ◽  
Entangled State ◽  
Quantum Protocols ◽  
Original Message

It is thought that the techniques operating entangled states are some of the principal ones in quantum information processing. Therefore, procedures constructing other types of entangled states from some entangled states are useful. In this paper, we first show methods that dynamically change the number of entangled qubits during communication. Next, we propose a sharing protocol called the anonymous entangled state sharing protocol. By using this protocol, a party's message can be split among unknown parties because the parties can share entangled states without knowing each other. Finally, we show protocols that can recover an original message and split it to other parties without revealing its shared messages.

scholarly journals Decoherence-Free Quantum Information Processing with Four-Photon Entangled States

2004 ◽  
Vol 92 (10) ◽  
Author(s):  
Mohamed Bourennane ◽  
Manfred Eibl ◽  
Sascha Gaertner ◽  
Christian Kurtsiefer ◽  
Adán Cabello ◽  
...  
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Entangled States
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