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We derive an analytical expression for the lower bound of the concurrence of mixed quantum states of composite 2xK systems. In contrast to other, implicitly defined entanglement measures, the numerical evaluation of our bound is…

Quantum Physics · Physics 2009-11-10 Artur Lozinski , Andreas Buchleitner , Karol Zyczkowski , Thomas Wellens

While the detection of entanglement has been proved already to be quite a difficult task, experimental quantification of entanglement is even more challenging. In this work, we derive an analytical lower bound for the concurrence of a…

Quantum Physics · Physics 2011-04-07 Zhi-Hao Ma , Zhi-Hua Chen , Jing-Ling Chen

Many protocols and experiments in quantum information science are described in terms of simple measurements on qubits. However, in a real implementation, the exact description is more difficult, and more complicated observables are used.…

Quantum Physics · Physics 2010-09-28 Tobias Moroder , Otfried Gühne , Normand J. Beaudry , Marco Piani , Norbert Lütkenhaus

We study the concurrence of arbitrary multipartite mixed quantum states. An explicit lower bound of the concurrence is derived, which detects quantum entanglement of some states better than some separability criteria, and gives sufficient…

Quantum Physics · Physics 2009-11-13 Ming Li , Shao-Ming Fei , Zhi-XiWang

In this paper, we investigate a genuine multipartite entanglement measure based on the geometric method. This measure arrives at the maximal value for the absolutely maximally entangled states and has desirable properties for quantifying…

Quantum Physics · Physics 2022-06-07 Xian Shi

We introduce a method to lower bound an entropy-based measure of genuine multipartite entanglement via nonlinear entanglement witnesses. We show that some of these bounds are tight and explicitly work out their connection to a framework of…

Quantum Physics · Physics 2012-08-21 Jun-Yi Wu , Hermann Kampermann , Dagmar Bruß , Claude Klöckl , Marcus Huber

We present a lower bound of concurrence for four-partite systems in terms of the concurrence for $M\, (2\leq M\leq 3)$ part quantum systems and give an analytical lower bound for $2\otimes2\otimes2\otimes2$ mixed quantum sates. It is shown…

Quantum Physics · Physics 2018-01-03 Xue-Na Zhu , Ming Li , Shao-Ming Fei

We consider the mixed three-qubit bound entangled state defined as the normalized projector on the subspace that is complementary to an Unextendible Product Basis [C. H. Bennett et. al., Phys. Rev. Lett. 82, 5385 (1999)]. Using the fact…

Quantum Physics · Physics 2010-07-28 Cyril Branciard , Huangjun Zhu , Lin Chen , Valerio Scarani

We study the concurrence of arbitrary dimensional multipartite quantum systems. An explicit analytical lower bound of concurrence for four-partite mixed states is obtained in terms of the concurrences of tripartite mixed states. Detailed…

Quantum Physics · Physics 2017-10-31 Wei Chen , Xue-Na Zhu , Shao-Min Fei , Zhu-Jun Zheng

We investigate the lower bound obtained from experimental data of a quantum state $\rho$, as proposed independently by G\"uhne et al. and Eisert et al. for mixed states of three qubits. The measure we consider is the convex-roof extended…

Quantum Physics · Physics 2010-03-04 A. Osterloh , P. Hyllus

We present the generalized state-dependent entropic uncertainty relations in multiple measurements setting, and the optimal lower bound is obtained by considering different measurement sequences. We then apply this uncertainty relation to…

Quantum Physics · Physics 2023-06-05 Li-Hang Ren , Yun-Hao Shi , Jin-Jun Chen , Heng Fan

We define a multi-partite entanglement measure for stabilizer states, which can be computed efficiently from a set of generators of the stabilizer group. Our measure applies to qubits, qudits and continuous variables.

Quantum Physics · Physics 2007-05-23 David Fattal , Toby S. Cubitt , Yoshihisa Yamamoto , Sergey Bravyi , Isaac L. Chuang

Multipartite entanglement is a valuable resource for quantum technologies. However, detecting this resource can be challenging: for genuine multipartite entanglement, the detection may require global measurements that are hard to implement…

Quantum Physics · Physics 2024-11-22 Fei Shi , Lin Chen , Giulio Chiribella , Qi Zhao

Covariance matrices are a useful tool to investigate correlations and entanglement in quantum systems. They are widely used in continuous variable systems, but recently also for finite dimensional systems powerful entanglement criteria in…

Quantum Physics · Physics 2010-04-22 Oleg Gittsovich , Otfried Gühne

We explore the structure of multipartite quantum systems which are entangled in multiple degrees of freedom. We find necessary and sufficient conditions for the characterization of tripartite systems and necessary conditions for any number…

Quantum Physics · Physics 2013-01-16 Marcus Huber , Julio I. de Vicente

The geometric measure of entanglement of a pure quantum state is defined to be its distance to the space of product (seperable) states. Given an $n$-partite system composed of subsystems of dimensions $d_1,\ldots, d_n$, an upper bound for…

Quantum Physics · Physics 2018-05-09 Liqun Qi , Guofeng Zhang , Guyan Ni

The Schmidt coefficients capture all entanglement properties of a pure bipartite state and therefore determine its usefulness for quantum information processing. While the quantification of the corresponding properties in mixed states is…

Quantum Physics · Physics 2019-04-08 Gael Sentís , Christopher Eltschka , Otfried Gühne , Marcus Huber , Jens Siewert

In recent decades, various multipartite entanglement measures have been proposed by many researchers, with different characteristics. Meanwhile, Scott studied various interesting aspects of multipartite entanglement measures and he has…

Quantum Physics · Physics 2023-07-20 Saeed Haddadi

A contemporary technological milestone is to build a quantum device performing a computational task beyond the capability of any classical computer, an achievement known as quantum adversarial advantage. In what ways can the entanglement…

Quantum Physics · Physics 2020-02-05 Jacob D. Biamonte , Mauro E. S. Morales , Dax Enshan Koh

We provide analytical lower and upper bounds for entanglement of formation for bipartite systems, which give a direct relation between the bounds of entanglement of formation and concurrence, and improve the previous results. Detailed…

Quantum Physics · Physics 2012-11-05 Xue-Na Zhu , Shao-Ming Fei