We study global entangling properties of the system of coupled kicked tops testing various hypotheses and predictions concerning entanglement in quantum chaotic systems. In order to analyze the averaged initial entanglement production rate and the averaged asymptotic entanglement, various ensembles of initial product states are evolved. Two different ensembles with natural probability distribut...

The bilateral controlled NOT (CNOT) operation plays a key role in standard entanglement purification process, but the CNOT operation may not be the optimal joint operation in the sense that the output entanglement is maximized. In this paper, the CNOT operations in both the Schmidt-projection based entanglement concentration and the entanglement purification schemes are replaced with a general ...

Finding the optimal encoding strategies can be challenging for communication using quantum channels, as classical and quantum capacities may be superadditive. Entanglement assistance can often simplify this task, as the entanglement-assisted classical capacity for any channel is additive, making entanglement across channel uses unnecessary. If the entanglement assistance is limited, the picture...

We discuss the generation of two-atom entanglement inside a resonant microcavity under stimulated emission (STE) interaction. The amount of entanglement is shown based on different atomic initial state. For each kind of intial state, we obtain the entanglement period and the entanglement critical point, which are found to deeply depend on driving field density. In case of atomic state |ee〉, the...

We study the entanglement properties of a higher-integer-spin Affleck–Kennedy– Lieb–Tasaki model with quantum group symmetry in the periodic boundary condition. We exactly calculate the finite size correction terms of the entanglement entropies from the double scaling limit. We also evaluate the geometric entanglement, which serves as another measure for entanglement. We find the geometric enta...

We review the mathematics of the theory of entanglement measures. As well as giving proofs from first principles for some well-known and important results, we provide a sharpened version of a uniqueness theorem which gives necessary and sufficient conditions for an entanglement measure to coincide with the reduced von Neumann entropy on pure states. We also prove several versions of a theorem o...

We determine the degree of entanglement for two indistinguishable particles based on the tensor product structure, which is a framework for emphasizing entanglement founded on observational quantities. Our theory connects the canonical entanglement and entanglement based on occupation number for two fermions and for two bosons and shows that the entanglement measure, based on linear entropy, is...

We study quantum entanglement of bipartite CAR systems. We show that triangle inequality of von Neumann entropy does not hold in these systems. Meanwhile, we show non-separability in the sense of Florig-Summers for our CAR systems. Entanglement degrees by Narnhofer are generalized to an arbitrary, that is, not-necessarily commuting pair of general C∗-systems. These new entanglement degrees are ...

What can we learn about entanglement between individual particles in macroscopic samples by observing only the collective properties of the ensembles? Using only a few experimentally feasible collective properties, we establish an entanglement measure between two samples of spin-1/2 particles (as representatives of two-dimensional quantum systems). This is a tight lower bound for the average en...

We propose a method to improve the performance of two entanglement-based continuous-variable quantum key distribution protocols using noiseless linear amplifiers. The two entanglement-based schemes consist of an entanglement distribution protocol with an untrusted source and an entanglement swapping protocol with an untrusted relay. Simulation results show that the noiseless linear amplifiers c...