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cosenal committed Aug 24, 2015
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4 changes: 2 additions & 2 deletions matlab_notebook.tex
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Expand Up @@ -135,7 +135,7 @@ \section*{Generalized Bell states (Examples from \cite{Ghosh04})}
In the code that follows, the function \texttt{GenPauli(a,b,n)} generates the
matrix corresponding to the operator $W_{a,b}\in\Unitary(\complex^{n})$
defined in Eq.~\eqref{eq:generalized-Pauli-operators}.
\subsection*{$5$ states in $\complex^{5}\otimes\complex^{5}$}
\subsection*{$5$ maximally entangled states in $\complex^{5}\otimes\complex^{5}$}
\begin{verbatim}
n = 5;
gen_bells = [vec(GenPauli(0,0,n)), ...
Expand All @@ -153,7 +153,7 @@ \subsection*{$5$ states in $\complex^{5}\otimes\complex^{5}$}
0.9898
\end{verbatim} \color{black}

\subsection*{$6$ states in $\complex^{6}\otimes\complex^{6}$}
\subsection*{$6$ maximally entangled states in $\complex^{6}\otimes\complex^{6}$}
\begin{verbatim}
n = 6;
gen_bells = [vec(GenPauli(0,0,n)), ...
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26 changes: 20 additions & 6 deletions programs.tex
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Expand Up @@ -426,15 +426,13 @@ \subsubsection{Decomposable operator}
A \emph{decomposable} map $\Phi:\Lin(\Y)\rightarrow\Lin(\X)$ is a linear map that can
be represented as the sum of a completely positive map and a completely
co-positive map, that is, there exist two completely positive maps
$\Psi,\Xi:\Lin(\Y)\rightarrow\Lin(\X)$, such that, for any $Y\in\Lin(\Y)$,
$\Psi,\Xi:\Lin(\Y)\rightarrow\Lin(\X)$, such that
\begin{equation}
\Phi(Y) = \Psi(Y) + (\pt {\circ}\, \Xi)(Y),
\Phi = \Psi + \pt {\circ}\, \Xi,
\end{equation}
where $\pt$ denotes the transpose map.
\end{definition}



\subsubsection{Exploiting symmetries}

Whenever the ensemble of states we wish to distinguish exhibits some symmetry,
Expand Down Expand Up @@ -662,6 +660,22 @@ \subsubsection{Block-positive operators}
J(\Phi) \in \BPos(\X:\Y).
\end{equation}
\end{itemize}
In order to prove the equivalence, observe the following equation:
\begin{equation}
\label{eq:choi-positive}
(\I_{\X}\otimes y^{\ast})J(\Phi)(\I_{X}\otimes y) = \Phi(\overline{y}y^{\t}),
\end{equation}
which holds for every vector $y\in\Y$.
Since the operator $\overline{y}y^{\t}$ is positive semidefinite,
we have that (a) implies (b).
To see the converse, recall that every positive semidefinite operator can be
written as a positive linear combination of rank-$1$ positive semidefinite
operators. Therefore, from the property (b), it holds that
\begin{equation}
(\I_{\X}\otimes y^{\t})J(\Phi)(\I_{X}\otimes \overline{y}) = \Phi(yy^{\ast})
\in\Pos(\X),
\end{equation}
for every vector $y\in\Y$, and thus by linearity $\Phi$ is a positive mapping.

Dual to the fact that there are non-separable positive semidefinite operators
is the fact that there are block-positive operators, which are not
Expand Down Expand Up @@ -1107,7 +1121,7 @@ \section{Unambiguous state discrimination}
& y_{i,j} \in \real, \quad 1 \leq i,j \leq N, \quad i \neq j.\notag
\end{align}
\end{center}
In the next chapter we will see an application of this program for unambiguous
PPT-distinguishability. In particular, we will analyze a set of states where
In the next chapter we will see an application of this program to the problem of
unambiguous PPT-distinguishability. In particular, we will analyze a set of states where
the unambiguous PPT-distinsuishability is strictly lower than the regular
PPT-distinguishability calculated by the program of Section~\ref{sec:ppt-measurements-program}.
10 changes: 5 additions & 5 deletions thesis.brf
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Expand Up @@ -67,14 +67,14 @@
\backcite {Doherty02,Doherty04}{{39}{4.2.1}{subsection.4.2.1}}
\backcite {Piani06}{{42}{4.2.1}{section*.13}}
\backcite {Gharibian13}{{45}{4.2.2}{subsection.4.2.2}}
\backcite {Chruscinski2014}{{46}{4.2.2}{equation.4.2.44}}
\backcite {Doherty02,Doherty04}{{47}{4.2.3}{subsection.4.2.3}}
\backcite {Doherty02}{{48}{4.2.3}{equation.4.2.50}}
\backcite {Myhr09}{{49}{4.2.3}{equation.4.2.52}}
\backcite {Chruscinski2014}{{47}{4.2.2}{equation.4.2.46}}
\backcite {Doherty02,Doherty04}{{48}{4.2.3}{subsection.4.2.3}}
\backcite {Doherty02}{{49}{4.2.3}{equation.4.2.52}}
\backcite {Myhr09}{{49}{4.2.3}{equation.4.2.54}}
\backcite {Gharibi10}{{54}{4.4}{section.4.4}}
\backcite {Doherty04}{{54}{4.4}{section.4.4}}
\backcite {MartinGroetschel93}{{54}{4.4}{section.4.4}}
\backcite {Johnston2015}{{55}{4.4}{equation.4.4.69}}
\backcite {Johnston2015}{{55}{4.4}{equation.4.4.71}}
\backcite {Eldar03}{{55}{4.5}{section.4.5}}
\backcite {Yu12}{{57}{5}{chapter.5}}
\backcite {Yu14}{{57}{5}{chapter.5}}
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