# Witnessed Entanglement

@inproceedings{Brando2004WitnessedE, title={Witnessed Entanglement}, author={Fernando G. S. L. Brand{\~a}o and Reinaldo O. Vianna}, year={2004} }

We present a new measure of entanglement for mixed states. It can be approximately computable for every state and can be used to quantify all different types of multipartite entanglement. We show that it satisfies the usual properties of a good entanglement quantifier and derive relations between it and other entanglement measures.

## 37 Citations

Entanglement witnesses generated by positive maps

- PhysicsQuantum Inf. Process.
- 2015

Positive maps based on one and two given quantum states are constructed, and entanglement witnesses are generated by composing the positive maps with affine maps.

Shining Light Over Mathematical Abstractions: a Direct Measurement of the Geometry of Entanglement

- Physics
- 2007

We develop a general approach to investigate the geometry of the set of different kinds of entangled states. We provide the first measurements of the border of the set of separable states for two…

Estimating entanglement of unknown states

- Physics
- 2006

The experimental determination of entanglement is a major goal in the quantum information field. In general, the knowledge of the state is required in order to quantify its entanglement. Here we…

Viable entanglement detection of unknown mixed states in low dimensions

- Physics
- 2009

We explore procedures to detect entanglement of unknown mixed states, which can be experimentally viable. The heart of the method is a hierarchy of simple feasibility problems, which provides…

Floating Entanglement Witness Measure and Genetic Algorithm

- Computer Science
- 2007

A classical algorithm is introduced that computes floating entanglement witness measure which satisfies some of the usual properties of a goodEntanglement measure and provides a method for finding entanglements witness for a given entangled state.

Entanglement dynamics and geometry of quantum states: calculations and simulations

- Physics
- 2008

We analyze the dynamical behavior of entangled systems under the action of decoherence and its relation to the geometry of quantum states. Physical examples and an experimental simulation are also…

Geometrically induced singular behavior of entanglement

- Physics
- 2008

We show that the geometry of the set of quantum states plays a crucial role in the behavior of entanglement in different physical systems. More specifically, it is shown that singular points at the…

Witnessed entanglement and the geometric measure of quantum discord

- Mathematics
- 2012

We establish relations between geometric quantum discord and entanglement quantifiers obtained by means of optimal witness operators. In particular, we prove a relation between negativity and…

Entanglement distillation : a discourse on bound entanglement in quantum information theory

- Physics
- 2006

This thesis covers in a unified way the material presented in quant-ph/0403073,quantity/0502040, quant-Ph/0504160, quants/0510035, quant/0512012 and quant- ph/0603283.