scholarly journals Multipartite entanglement outperforming bipartite entanglement under limited quantum system sizes

2018 ◽  
Vol 98 (5) ◽  
Author(s):  
Hayata Yamasaki ◽  
Alexander Pirker ◽  
Mio Murao ◽  
Wolfgang Dür ◽  
Barbara Kraus
Keyword(s):  
Quantum System ◽  
Multipartite Entanglement ◽  
Bipartite Entanglement

scholarly journals Correlation loss and multipartite entanglement across a black hole horizon (

2009 ◽  
Vol 9 (7&8) ◽  
pp. 657-665
Author(s):  
G. Adesso ◽  
I. Fuentes-Schuller
Keyword(s):  
Black Hole ◽  
Small Mass ◽  
Point Of View ◽  
Multipartite Entanglement ◽  
Squeezed State ◽  
Schwarzschild Black Hole ◽  
Bipartite Entanglement ◽  
Hawking Effect ◽  
Entanglement Distribution ◽  
Quantum And Classical Correlations

We investigate the Hawking effect on entangled fields. By considering a scalar field which is in a two-mode squeezed state from the point of view of freely falling (Kruskal) observers crossing the horizon of a Schwarzschild black hole, we study the degradation of quantum and classical correlations in the state from the perspective of physical (Schwarzschild) observers confined outside the horizon. Due to monogamy constraints on the entanglement distribution, we show that the lost bipartite entanglement is recovered as multipartite entanglement among modes inside and outside the horizon. In the limit of a small-mass black hole, no bipartite entanglement is detected outside the horizon, while the genuine multipartite entanglement interlinking the inner and outer regions grows infinitely.

scholarly journals CHARACTERIZING AND MEASURING MULTIPARTITE ENTANGLEMENT

2007 ◽  
Vol 05 (01n02) ◽  
pp. 97-103 ◽  
Author(s):  
P. FACCHI ◽  
G. FLORIO ◽  
S. PASCAZIO
Keyword(s):  
Probability Density Function ◽  
Probability Density ◽  
Density Function ◽  
Multipartite Entanglement ◽  
Bipartite Entanglement ◽  
Pure States

A method is proposed to characterize and quantify multipartite entanglement in terms of the probability density function of bipartite entanglement over all possible balanced bipartitions of an ensemble of qubits. The method is tested on a class of random pure states.

scholarly journals Phase transitions and metastability in the distribution of the bipartite entanglement of a large quantum system

2010 ◽  
Vol 81 (5) ◽  
Author(s):  
A. De Pasquale ◽  
P. Facchi ◽  
G. Parisi ◽  
S. Pascazio ◽  
A. Scardicchio
Keyword(s):  
Phase Transitions ◽  
Quantum System ◽  
Bipartite Entanglement ◽  
Large Quantum

scholarly journals Multipartite entanglement and topology in holography

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Jonathan Harper
Keyword(s):  
Minimal Surface ◽  
Cross Section ◽  
Mixed State ◽  
Homology Class ◽  
Boundary Region ◽  
Multipartite Entanglement ◽  
Purification Procedure ◽  
Bipartite Entanglement ◽  
Original Boundary ◽  
And Topology

Abstract Starting from the entanglement wedge of a multipartite mixed state we describe a purification procedure which involves the gluing of several copies. The resulting geometry has non-trivial topology and a single oriented boundary for each original boundary region. In the purified geometry the original multipartite entanglement wedge cross section is mapped to a minimal surface of a particular non-trivial homology class. In contrast, each original bipartite entanglement wedge cross section is mapped to the minimal wormhole throat around each boundary. Using the bit thread formalism we show how maximal flows for the bipartite and multipartite entanglement wedge cross section can be glued together to form maximal multiflows in the purified geometry. The defining feature differentiating the flows is given by the existence of threads which cross between different copies of the original entanglement wedge. Together these demonstrate a possible connection between multipartite entanglement and the topology of holographic spacetimes.

scholarly journals Genuine multipartite entanglement in time

2021 ◽  
Vol 10 (6) ◽  
Author(s):  
Simon Milz ◽  
Cornelia Spee ◽  
Zhen-Peng Xu ◽  
Felix Pollock ◽  
Kavan Modi ◽  
...  
Keyword(s):  
Sufficient Conditions ◽  
Quantum Correlations ◽  
Multipartite Entanglement ◽  
Quantum Processes ◽  
Bipartite Entanglement ◽  
Temporal Correlations ◽  
Crucial Difference ◽  
Comprehensive Picture ◽  
Quantum Steering ◽  
Genuine Multipartite Entanglement

While spatial quantum correlations have been studied in great detail, much less is known about the genuine quantum correlations that can be exhibited by temporal processes. Employing the quantum comb formalism, processes in time can be mapped onto quantum states, with the crucial difference that temporal correlations have to satisfy causal ordering, while their spatial counterpart is not constrained in the same way. Here, we exploit this equivalence and use the tools of multipartite entanglement theory to provide a comprehensive picture of the structure of correlations that (causally ordered) temporal quantum processes can display. First, focusing on the case of a process that is probed at two points in time -- which can equivalently be described by a tripartite quantum state -- we provide necessary as well as sufficient conditions for the presence of bipartite entanglement in different splittings. Next, we connect these scenarios to the previously studied concepts of quantum memory, entanglement breaking superchannels, and quantum steering, thus providing both a physical interpretation for entanglement in temporal quantum processes, and a determination of the resources required for its creation. Additionally, we construct explicit examples of W-type and GHZ-type genuinely multipartite entangled two-time processes and prove that genuine multipartite entanglement in temporal processes can be an emergent phenomenon. Finally, we show that genuinely entangled processes across multiple times exist for any number of probing times.

scholarly journals ENTANGLEMENT FRUSTRATION IN MULTIMODE GAUSSIAN STATES

2012 ◽  
Vol 09 (02) ◽  
pp. 1260022 ◽  
Author(s):  
COSMO LUPO ◽  
STEFANO MANCINI ◽  
PAOLO FACCHI ◽  
GIUSEPPE FLORIO ◽  
SAVERIO PASCAZIO
Keyword(s):  
Pure State ◽  
High Energy ◽  
Quantum Systems ◽  
Entangled States ◽  
Multipartite Entanglement ◽  
Total System ◽  
Continuous Variables ◽  
Bipartite Entanglement ◽  
Gaussian States ◽  
Composite Quantum System

Bipartite entanglement between two parties of a composite quantum system can be quantified in terms of the purity of one party and there always exists a pure state of the total system that maximizes it (and minimizes purity). When many different bipartitions are considered, the requirement that purity be minimal for all bipartitions gives rise to the phenomenon of entanglement frustration. This feature, observed in quantum systems with both discrete and continuous variables, can be studied by means of a suitable cost function whose minimizers are the maximally multipartite-entangled states (MMES). In this paper we extend the analysis of multipartite entanglement frustration of Gaussian states in multimode bosonic systems. We derive bounds on the frustration, under the constraint of finite mean energy, in the low- and high-energy limits.

scholarly journals Unified Monogamy Relations of Multipartite Entanglement

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Awais Khan ◽  
Junaid ur Rehman ◽  
Kehao Wang ◽  
Hyundong Shin
Keyword(s):  
Analytic Formula ◽  
Entangled States ◽  
Multipartite Entanglement ◽  
Entanglement Measure ◽  
Mixed States ◽  
Bipartite Entanglement ◽  
Entanglement Of Formation ◽  
Special Cases ◽  
Qubit States ◽  
Monogamy Relations

Abstract Unified-(q, s) entanglement $$({{\mathscr{U}}}_{q,s})$$ ( U q , s ) is a generalized bipartite entanglement measure, which encompasses Tsallis-q entanglement, Rényi-q entanglement, and entanglement of formation as its special cases. We first provide the extended (q; s) region of the generalized analytic formula of  $${{\mathscr{U}}}_{q,s}$$ U q , s . Then, the monogamy relation based on the squared  $${{\mathscr{U}}}_{q,s}$$ U q , s for arbitrary multiqubit mixed states is proved. The monogamy relation proved in this paper enables us to construct an entanglement indicator that can be utilized to identify all genuine multiqubit entangled states even the cases where three tangle of concurrence loses its efficiency. It is shown that this monogamy relation also holds true for the generalized W-class state. The αth power $${{\mathscr{U}}}_{q,s}$$ U q , s based general monogamy and polygamy inequalities are established for tripartite qubit states.

The negativity of partial transpose versus the negativity of Wigner function

2019 ◽  
Vol 16 (06) ◽  
pp. 1930003 ◽  
Author(s):  
Mustapha Ziane ◽  
Fatima-Zahra Siyouri ◽  
Morad El Baz ◽  
Yassine Hassouni
Keyword(s):  
Hilbert Space ◽  
Phase Space ◽  
Wigner Function ◽  
Coherent States ◽  
Good Measure ◽  
Multipartite Entanglement ◽  
Bipartite Entanglement ◽  
Different Types ◽  
Partial Transpose

We investigate the multipartite entanglement in the phase space using the negativity of Wigner function (NWF) and in the Hilbert space using the negativity of partial transpose (NPT). We analyze comparatively these quantities and the different types of entanglements that are present in two major classes — GHZ and [Formula: see text] — made of coherent states. We show that the negativity of Wigner function can be used as a good measure of genuine entanglement in multipartite systems. However, the negativity of partial transpose is a good quantifier for only the bipartite entanglement in tripartite systems.

scholarly journals Relations between bipartite entanglement measures

2018 ◽  
Vol 18 (1&2) ◽  
pp. 85-113 ◽  
Author(s):  
Katharina Schwaiger ◽  
Barbara Kraus
Keyword(s):  
Pure State ◽  
Single Copy ◽  
Point Of View ◽  
Multipartite Entanglement ◽  
Bipartite Entanglement ◽  
Classical Communication ◽  
Main Emphasis ◽  
Entanglement Measures ◽  
Pure States

We investigate the entanglement of bipartite systems from an operational point of view. Main emphasis is put on bipartite pure states in the single copy regime. First, we present an operational characterization of bipartite pure state entanglement, viewing the state as a multipartite state. Then, we investigate the properties and relations of two classes of operational bipartite and multipartite entanglement measures, the so-called source and the accessible entanglement. The former measures how easy it is to generate a given state via local operations and classical communication (LOCC) from some other state, whereas the latter measures the potentiality of a state to be convertible to other states via LOCC. We investigate which parameter regime is physically available, i.e. for which values of these measures does there exist a bipartite pure state. Moreover, we determine, given some state, which parameter regime can be accessed by it and from which parameter regime it can be accessed. We show that this regime can be determined analytically using the Positivstellensatz. We compute the boundaries of these sets and the boundaries of the corresponding source and accessible sets. Furthermore, we relate these results to other entanglement measures and compare their behaviors.

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