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2024-02-18 19:48:17 -08:00
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3 changed files with 39 additions and 34 deletions

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@ -174,11 +174,6 @@ Say $[x] = [\nicefrac{2}{3}, \nicefrac{1}{3}]$ and $[y] = [\nicefrac{3}{4}, \nic
\problem{}
With $x$ and $y$ defined as above, find the probability of measuring each of \texttt{00}, \texttt{01}, \texttt{10}, and \texttt{11}.
\vfill
\problem{}
Say $[x] = [\nicefrac{2}{3}, \nicefrac{1}{3}]$ and $[y] = [\nicefrac{3}{4}, \nicefrac{1}{4}]$. \par
What is the probability that $x$ and $y$ produce different outcomes?
@ -324,27 +319,30 @@ In other words, what is the set of vectors that can be written as linear combina
\vfill
Look through the above problems and convince yourself of the following fact: \par
If $a$ is a basis of $A$ and $b$ is a basis of $B$, $a \otimes b$ is a basis of $A \times B$. \par
\note{If you don't understand what this says, ask an instructor. \\ This is the reason we did the last few problems!}
\begin{instructornote}
\textbf{The idea here is as follows:}
If $a$ is in $\{\texttt{0}, \texttt{1}\}$ and $b$ is in $\{\texttt{0}, \texttt{1}\}$,
the values $ab$ can take are
$\{\texttt{0}, \texttt{1}\} \times \{\texttt{0}, \texttt{1}\} = \{\texttt{00}, \texttt{01}, \texttt{10}, \texttt{11}\}$.
\vspace{2mm}
The same is true of any other state set: if $a$ takes values in $A$ and $b$ takes values in $B$, \par
the compound state $(a,b)$ takes values in $A \times B$.
\vspace{2mm}
We would like to do the same with probabilistic bits. \par
Given bits $\ket{a}$ and $\ket{b}$, how should we represent the state of $\ket{ab}$?
\end{instructornote}
% This is wrong, but there's something here.
% maybe fix later?
%
%Look through the above problems and convince yourself of the following fact: \par
%If $a$ is a basis of $A$ and $b$ is a basis of $B$, $a \otimes b$ is a basis of $A \times B$. \par
%\note{If you don't understand what this says, ask an instructor. \\ This is the reason we did the last few problems!}
%
%\begin{instructornote}
% \textbf{The idea here is as follows:}
%
% If $a$ is in $\{\texttt{0}, \texttt{1}\}$ and $b$ is in $\{\texttt{0}, \texttt{1}\}$,
% the values $ab$ can take are
% $\{\texttt{0}, \texttt{1}\} \times \{\texttt{0}, \texttt{1}\} = \{\texttt{00}, \texttt{01}, \texttt{10}, \texttt{11}\}$.
%
% \vspace{2mm}
%
% The same is true of any other state set: if $a$ takes values in $A$ and $b$ takes values in $B$, \par
% the compound state $(a,b)$ takes values in $A \times B$.
%
% \vspace{2mm}
%
% We would like to do the same with probabilistic bits. \par
% Given bits $\ket{a}$ and $\ket{b}$, how should we represent the state of $\ket{ab}$?
%\end{instructornote}
\pagebreak
@ -453,7 +451,7 @@ Consider the NOT gate, which operates as follows: \par
\end{itemize}
What should NOT do to a probabilistic bit $[x_0, x_1]$? \par
If we return to our coin analogy, we can think of the NOT operation as
flipping a coin we have already tossed, without looking at it's state.
flipping a coin we have already tossed, without looking at its state.
Thus,
\begin{equation*}
\text{NOT} \begin{bmatrix}
@ -544,8 +542,8 @@ Find the matrix that represents the NOT operation on one probabilistic bit.
\problem{Extension by linearity}
Say we have an arbitrary operation $A$. \par
If we know how $A$ acts on $[1]$ and $[0]$, can we compute $A[x]$ for an arbitrary state $[x]$? \par
Say we have an arbitrary operation $M$. \par
If we know how $M$ acts on $[1]$ and $[0]$, can we compute $M[x]$ for an arbitrary state $[x]$? \par
Say $[x] = [x_0, x_1]$.
\begin{itemize}
\item What is the probability we observe $0$ when we measure $x$?