The structural physical approximation (SPA) to a positive map is considered to be one of the
most important methods to detect entanglement in the real physical world. We first show that …

Quantum entanglement lies at the heart of quantum mechanics and quantum information
processing. In this work, we show a framework where entangled states play the role of …

We present an analysis of the properties and characteristics of weakly optimal entanglement
witnesses, that is witnesses whose expectation value vanishes on at least one product …

In open quantum systems, it is known that if the system and environment are in a product
state, the evolution of the system is given by a linear completely positive (CP) Hermitian …

Any bipartite entanglement witness W can be written as W= c σ I− σ, where σ is a quantum
state, I is the identity matrix, and c σ is a non-negative number. We present a general method …