Entanglement is a complexity measure for directed graphs that was used to show that the variable hierarchy of the propositional modal μ-calculus is strict. While graphs of entanglement zero and one are indeed very simple, some graphs of entanglement two already contain interesting nesting of cycles. This motivates our study of the class of graphs of entanglement two, as these are both simple in...

Computations in a distributed environment comprising a network of spatially separated nodes may require the exchange of classical and quantum information. The amount of classical communication may be reduced in such computations by using multipartite entanglement. Following the combinatorial approach developed in [25, 27], we study entanglement configurations over a set of nodes, where each ent...

Entanglement is a parameter for the complexity of finite directed graphs that measures to which extent the cycles of the graph are intertwined. It is defined by way of a game similar in spirit to the cops and robber games used to describe tree width, directed tree width, and hypertree width. Nevertheless, on many classes of graphs, there are significant differences between entanglement and the ...

Quantum entanglement is an essential resource for many quantum communication protocols, such as teleportation [1,2] and dense coding [3,4], allowing an information processing efficiency, which is otherwise unattainable through classical protocols. As such the efficiency of those quantum protocols relies on the ability to isolate the encoding system, being strongly decreased when the system is c...

We characterize the multipartite entanglement of a system of n qubits in terms of the distribution function of the bipartite purity over all balanced bipartitions. We search for those (maximally multipartite entangled) states whose purity is minimum for all bipartitions and recast this optimization problem into a problem of statistical mechanics. PACS numbers: 03.67.Mn, 03.65.Ud, 89.75.−k, 03.6...

So-called direct measurements of entanglement are collective measurements on multiple copies of a (bipartite or multipartite) quantum system that directly provide one a value for some entanglement measure, such as the concurrence for bipartite states. Multiple copies are needed since the entanglement of a mixed state is not a linear function of the density matrix. Unfortunately, so far all expe...

Entanglement entropy is a statistical entropy measuring information loss due to coarse-graining corresponding to a spatial division of a system. In this paper we construct a thermodynamics (entanglement thermodynamics) which includes the entanglement entropy as the entropy variable, for a massless scalar field in Minkowski, Schwarzschild and Reissner-Nordström spacetimes to understand the stati...

We show how entanglement shared between encoder and decoder can simplify the theory of quantum error correction. The entanglement-assisted quantum codes we describe do not require the dual-containing constraint necessary for standard quantum error-correcting codes, thus allowing us to "quantize" all of classical linear coding theory. In particular, efficient modern classical codes that attain t...

Quantum mechanics has many counter-intuitive consequences which contradict our intuition which is based on classical physics. Here we discuss a special aspect of quantum mechanics, namely the possibility of entanglement between two or more particles. We will establish the basic properties of entanglement using quantum state teleportation. These principles will then allow us to formulate quantit...

The problem of demonstrating entanglement is central to quantum information processing applications. Resorting to standard entanglement witnesses requires one to perfectly trust the implementation of the measurements to be performed on the entangled state, which may be an unjustified assumption. Inspired by the recent work of F. Buscemi [Phys. Rev. Lett. 108, 200401 (2012)], we introduce the co...