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 ...

We demonstrate the dependence of the entanglement dynamics on the global classical regime of regular, mixed and chaotic dynamics with initial squeezed coherent states. By squeezing the initial states, we are able to enhance or suppress the entanglement entropy of the dynamically generated quantum states relative to those produced via initial coherent states. This suggests the possibility of exp...

Studies of entanglement in many-particle systems suggest that most quantum critical ground states have infinitely more entanglement than noncritical states. Standard algorithms for one-dimensional systems construct model states with limited entanglement, which are a worse approximation to quantum critical states than to others. We give a quantitative theory of previously observed scaling behavi...

We demonstrated entanglement distribution between two remote quantum nodes located 3 meters apart. This distribution involves the asynchronous preparation of two pairs of atomic memories and the coherent mapping of stored atomic states into light fields in an effective state of near-maximum polarization entanglement. Entanglement is verified by way of the measured violation of a Bell inequality...

Entanglement is at the heart of quantum technologies such as quantum information and quantum metrology. Providing larger quantum Fisher information (QFI), entangled systems can be better resources than separable systems in quantum metrology. However the effects on the entanglement dynamics such as decoherence usually decrease the QFI considerably. On the other hand, Dzyaloshinskii-Moriya (DM) i...

Nonlocality is at the heart of quantum information processing. In this paper we investigate the minimum amount of classical communication required in order to simulate a nonlocal quantum measurement. We derive general upper bounds, which in turn translate to systematic classical simulations of quantum communication protocols. As a concrete application, we prove that any quantum communication pr...

We present basics of mixed-state entanglement theory. The first part of the article is devoted to mathematical characterizations of entangled states. In second part we discuss the question of using mixed-state entanglement for quantum communication. In particular, a type of entanglement that is not directly useful for quantum communcation (called bound entanglement) is analysed in detail. This ...

The entanglement dynamics of a quantum register with two or three two-level atoms interacting with a common environment is analytically studied by the quantum jump method. In contrast to the usual belief that the environment plays a role of destroying the entanglement, it is found that the environment can also produce stable entanglement between the qubits that are prepared initially in a separ...

We review recent experiments concerning multi-photon Greenberger–Horne– Zeilinger (GHZ) entanglement. We have experimentally demonstrated GHZ entanglement of up to four photons by making use of pulsed parametric downconversion. On the basis of measurements on three-photon entanglement, we have realized the first experimental test of quantum non-locality following from the GHZ argument. Not only...

Macroscopic quantum phenomena, e.g., superconductivity and squeezing, are believed to result from entanglement of macroscopic numbers of particles. We report the first direct study of this kind of entanglement: we use discrete quantum tomography to reconstruct the joint quantum state of photon pairs extracted from polarization-squeezed light. Our observations confirm several predictions from sp...