We study genuine multipartite entanglement (GME) and multipartite k-entanglement based on q-concurrence. Well-defined parameterized GME measures and measures of multipartite k-entanglement are presented for arbitrary dimensional n-partite quantum systems. Our GME measures show that the GHZ state is more entangled than the W state. Moreover, our measures are shown to be inequivalent to the existing measures according to entanglement ordering. Detailed examples show that our measures characterize the multipartite entanglement finer than some existing measures, in the sense that our measures identify the difference of two different states while the latter fail.
We study genuine multipartite entanglement (GME) and multipartite k-entanglement based on q-concurrence. Well-defined parameterized GME measures and measures of multipartite k-entanglement are presented for arbitrary dimensional n-partite quantum systems. Our GME measures show that the GHZ state is more entangled than the W state. Moreover, our measures are shown to be inequivalent to the existing measures according to entanglement ordering. Detailed examples show that our measures characterize the multipartite entanglement finer than some existing measures, in the sense that our measures identify the difference of two different states while the latter fail.
Genuine Multipartite Entanglement Measure Based on α-concurrence
Quantifying genuine entanglement is a crucial task in quantum information theory. Based on the geometric mean of bipartite α-concurrences among all bipartitions, we present a class of well-defined genuine multipartite entanglement (GME) measures GαC with one parameter α for arbitrary multipartite states. We show that the GαC is of continuity for any multipartite pure states. By utilizing the related symmetry, analytical results of GαC are derived for any n-qubit GHZ states and W states, which show that the GHZ states are more genuinely entangled than the W states. With explicit examples, we demonstrate that the GαC can distinguish different GME states that other GME measures fail to. These results justify the potential applications of GαC in characterizing genuine multipartite entanglements.
Abstract We introduce G ω -GME, a family of genuine multipartite entanglement measures defined via the geometric mean of a parameterized bipartite concurrence. We prove that G ω -GME satisfies all GME axioms, derive analytical expressions for GHZ and W states, and establish a strict entanglement hierarchy. Continuity under state perturbations is proven with explicit bounds. Compared with genuinely multipartite concurrence, GqC, and G α C, G ω -GME resolves finer entanglement structures and offers greater flexibility through its extended parameter range. These features make G ω -GME a powerful and practical tool for multipartite entanglement quantification and quantum network certification.
Abstract This chapter takes a closer look at entanglement in multipartite systems. An examination of pure tripartite systems serves a starting point from which we discover the equivalence classes of Greenberger-Horne-Zeilinger (GHZ) states and W states. We then continue with the mixed-state case and discuss the notions of full separability, partition-separability and biseparability versus genuine tripartite entanglement, before stating the GHZ theorem in the formulation following Mermin. For systems of three or more parties we then formulate the definitions for k-separability and genuine multipartite entanglement (GME), as well as for k-producibility and entanglement depth, followed by prominent examples for GME states such as the generalized GHZ states and Dicke states. We give an overview of the problem of detecting GME using various linear and non-linear GME witnesses, lifted witnesses, PPT mixers, before discussing challenges for the characterization and quantification of multipartite entanglement. We close by analysing the phenomenon of entangled entanglement.
Multipartite entanglement is a fundamental aspect of quantum mechanics, crucial to advancements in quantum information processing and quantum computation. Within this field, Genuinely Multipartite Entanglement (GME), being entangled in all bipartitions, and Absolutely Maximally Entanglement (AME), maximally entangled in all bipartitions, represent two significant types of entanglement with diverse applications. In this work, we introduce a new measure called the GME-AME multipartite entanglement measure, with a non-zero value representing the GME states and the maximum value is reached only by the AME states. The measure is applied to study the multipartite entanglement of four partite systems using the operator to state mapping, and the four partite permutation qutrit states are classified according to the measure. With various examples, we show that our measure is robust in classifying the four partite entangled states.
Genuine multipartite entanglement (GME) is a valuable resource for quantum technologies, but quantifying it in many-body systems can be demanding since measures defined through optimizations over bipartitions are often assumed to require large joint measurements and many measurement settings. We introduce the concepts of GME evaluation length and GME evaluation number, which capture, respectively, the largest subsystem that must be jointly measured and the number of distinct subsystems that need to be measured to evaluate multipartite entanglement measures defined via bipartition optimizations. Taking the genuine multipartite concurrence (GMC) as a canonical example, we show that, for N-qubit Haar-random pure states, the GMC can be evaluated using only N single-qubit purity measurements. Thus, for typical many-body states, evaluating the GMC requires considering only the N single-site bipartitions, rather than the exponentially many distinct bipartitions. We further corroborate this behavior numerically for physically accessible states generated by local random quantum circuits. Our results show that the practical cost of quantifying GME can be dramatically lower than suggested by its formal definition, establishing measurement complexity as a complementary operational lens for multipartite entanglement.
ABSTRACT Entanglement is a fundamental resource in quantum information science. In this work, we introduce the geometric total concurrence (GTC), a new measure of genuine multipartite entanglement (GME) for ‐partite systems based on the concept of total concurrence. The GTC satisfies a key criterion by assigning higher entanglement to GHZ states than to W states. We derive analytically computable lower bounds for the GTC using PPT and realignment criteria. Furthermore, we show that the GTC induces an entanglement ordering distinct from existing measures, providing a unique perspective on multipartite correlations. Through detailed examples, we demonstrate that the GTC offers improved sensitivity in detecting entanglement and sharper discrimination among different types of entangled states, establishing it as a practical tool for characterizing and quantifying GME.