## Represents the state of a qubit as a point on the Bloch sphere

Jul 23, 2012  | by

In the chapter 1.2 of Michael Nielsen’s book Quantum Comutation and Quantum Information, it is said that the state of a qubit could be rewritten as $$\label{eq_bloch} |\psi\rangle = \cos\frac{\theta}{2}|0\rangle + e^{i\varphi}\sin\frac{\theta}{2}|1\rangle,$$ but the inference procedure was not given. Here we try to infer it.

## 面对面的办公室——纪念艾伦•图灵百年诞辰

Jun 22, 2012  | by

## LaTeX Beamer: display outline at the beginning of each section

Aug 13, 2011  | by

Use the following code snip

\AtBeginSubsection{
\begin{frame}{Outline}
\tableofcontents[currentsection,currentsubsection]
\end{frame}
}

## Disable spotlight indexing on OS X Lion or Mountain Lion

Jul 17, 2011  | by

Mac OS X Spotlight search is a powerful beast, returning all types of search results in seconds. However, if you don’t use it to launch apps, or find files then it can take up precious CPU cycles for no good reason.

## How to add user to a group from Mac OS X command line

Nov 23, 2010  | by

Use the following commands to add user to a group:

sudo dseditgroup -o edit -a usernametoadd -t user admin
sudo dseditgroup -o edit -a usernametoadd -t user wheel

© 2015 Haixing Hu with help from Jekyll Bootstrap and Twitter Bootstrap